5G home internet keeps dropping

Thank you for your work, if only we could all be as persistent. Annoy the life out of the company as long as you have problems.

I am currently troubleshooting the same issue. My set up is the trashcan connected to the WAN, fire walled, side of an Asus ac68u. The Asus is handling all LAN Wi-Fi DHCP etc. I just did a test hooking up a Roku directly to the trashcan (using the 2nd Ethernet connection) at the same time that the Asus was showing the Internet down, The Roku was able to still stream on it’s wired connection.
 

My current working hypothesis is there is some incompatibility between the trashcan and a separate router (LAN side) vs the t-mobile is dropping the internet (WAN Side) my prior working hypothesis). 
 

This seems unrelated, but I wonder if there is some MTU incompatibility between the WAN side of the asus and the LAN side of the trash can. https://amithkumarg.medium.com/resolved-t-mobile-home-internet-vpn-issue-2f5ca594c23e Does not seem too easy to change the MTU on the asus though. 

Since once the power goes off it switches to battery anything that interrupts the power will not work well. I mean yea after a few min off it will boot to battery then if you put the power back it should boot but not sure this is a good idea. Also yes you drop the internet so that is a monkey wrench too.

I think a small script that logs in and executes the reboot is probably the best amd clean.

The Nokia router has 4 U.FL connectors, one for each antenna. The U.FL connectors are small and making the connection takes great care. When seated properly there is a distinctive click feel as the U.FL connector seats. This is a mechanical connection. The location of these U.FL connectors in the router does not offer a huge amount of real estate so making these connections would take care and focus. Maybe some of these are not connected firmly. It would take 5-10 minutes to confirm this and it might explain signal connectivity issues if this were the case. It might be a long shot but maybe not. If the cellular statistics report packet errors or drops I would investigate this. The guide waveform has is excellent so checking this is super easy. One point I would like to clarify is that IF you ever need to remove the SIM be sure to have the router horizontal with the SIM card holder so that the retention screw is to the right of the SIM when removing the SIM. There is nothing holding the SIM in the holder so if it is in a vertical position when the SIM tray is removed the SIM will fall out of the SIM tray. Just pay close attention to details as progress is made. If the U.FL connectors are checked and they look to be seated properly I would not disconnect them as they are rather delicate but careful examination would not hurt anything. Removal of the shell of the can is easy. Just take a look at the guide and read each step. If you don’t feel comfortable doing so or don’t have the tools that is fine. Getting a replacement router might be possible, in time, but also offers the possibility of introducing new variables. 

Link to waveform guide: t-mobile-5g-gateway

OK you are troubleshooting intermittent connectivity. Let’s break this down just a little. Your solution with the ASUS and the Pi-Hole network-level advertisement and internet tracker blocker opens a whole plethora of variables. The Pi-Hole is a creative, interesting software solution. It acts as a DNS server but what big boy DNS server upstream does it use? I would probably test with pings to the Google, Quad9 and CloudFlare DNS servers and pick the one with the lowest latency to point the Pi-Hole at to feed it what it needs. Given the Pi-Hole sits in the middle maybe in the tools folder there are some useful trinkets. Even without clever tools in the Pi-Hole I would speculate you have  a Linux client or two, I do. Using the terminal and “netstat” there are various options for how to get the facts and build what we know vs. what we think. Taking packet captures and doing analysis on the functions of sessions is another option. Using Wireshark or taking a tcpdump can provide important clues. I don’t have a Pi-Hole but I can download it and install it on one of my Linux clients to tinker with. Since I have not used the Pi-Hole software I am not the best resource on that solution but I find it very interesting. If you suspect an incompatibility between the Nokia router and another router/device then look at the communication across these devices. The answers are quite possibly in the frames/packets, session information, from the TCP/IP stack etc… There could be some issue that looks like an incompatibility but is really just a fundamental bug. With the data you will have the silver bullet to put the wolf down. 

On a side note. I observed first hand that if I leave a HTTP session with the Nokia router too long, I have not timed this, the web UI of the Nokia router will report no network connection. I used my MacBook with CAT 6 direct to LAN 1 on the router and a Linux client with a wireless connection. I opened three terminal windows and ran simultaneous pings to the Google DNS, Quad9, and CloudFlare DNS servers. All the pings went right on through and the router was really connected to the tower but the web UI reported incorrect information. I closed the tab and opened a new session to the Nokia router and taadaa the router reported the real facts. Sometimes it takes multiple forks to get proper confirmation and it takes time. I am sure you are putting considerable time into your solution given it is not a garden variety solution. You stated the ASUS was reporting the internet down but how do we quantify that? It seems similar to when I observed, on multiple occasions, the web UI of the router HTTP server being unresponsive. Sure I should have taken packet captures to confirm which side of the session was being mute but it was not that important to me as I know how to work around it. It may be how the Nokia router caches information and when the session fails it acts like Jack Oneall in Stargate, “I got nothin.” I could be accused of that at times. :-)

I have spent most of my time investigating the network disconnects with ONLY the T-Mobile Nokia router and my local clients. I know it seems rather rudimentary but it has worked for me quite well. I did 3rd level network troubleshooting for +20 years on enterprise networks so since I retired I have taken a little more relaxed approach to my current network solution. I currently have over 10 days of uninterrupted uptime on my network with just the Nokia router so the KISS principle does have some merit. There are some interesting posts out on the web but don’t let all that chatter take you too far down the rabbit hole. Look at the basics before jumping to the more complex thoughts. Taking packet captures will provide hard data points so you know what you know and not think what you know. My father always told me if you know the why you can figure out the how. It works for me. Around 20 years ago a network escalation engineer told me, “I don’t want to know what you think. I want to know what you know.” I listened to Dave and became a much better engineer. I ended up taking his seat in the office in CA and did the job for +20 years. The key was to open my mind, eat humble pie, and dig for facts. I was also fortunate to have landed in a position with some very creative team members who all became great friends. 

The T-Mobile “router/gateway” may not be God’s gift to mankind but it is not a “trashcan”. Don’t let others put a negative spin in your head. Think for yourself and determine if you really think it is a trashcan or not. I have found it very limiting for visibility to the actual network operations but in the end with careful investigation working around its limitations I managed to obtain a stable solution. The problems I had with these same issues were not with the Nokia router but with the cellular equipment on the tower. By working with the T-Mobile support engineers I was able to see the problem through. It did take a couple of weeks before things became stable but they fixed the problems. I get 10X the download and upload speeds I got in CA for less money using the T-Mobile home internet solution. It was a huge win for me. If it ain’t broke don’t fix it. If you can get some hard data and I can help out I will try. Please just call it a router and keep it neutral. Best wishes!

Sorry I did not intentionally ignore the reference to the MTU size that Amith Kamur discusses. He is obviously a very intelligent and talented engineer. His article is well written and offers a solution where the use of the VPN is desired. Encountering MTU issues can be possible, and maybe pretty common, as the VPN adds overhead to the solution with the size of the packet. You have to limit the data contained to have the wrapper small enough so every node along the path can handle the MTU. If you stated you use a VPN regularly I would have taken more focus on that but well. As you state, may be unrelated, and I would not rush down that rabbit holeright away. Analysis of packet captures and looking at the physical layer and moving up the stack from the bottom up would be more productive. 

Do yourself a favor and use www.cellmapper.net to learn where the T-Mobile towers are. Record the information about the ones close to or around you with attention to the PCI (physical cell ID). If you go into the router with the web UI at 192.168.12.1 you will see the primary and secondary channels/signals on the overview page. That will show you the connections and RSRP/RSRQ/SNR values to know the signal strength, signal quality, and signal to noise ratio. Then go to the status page and record the band, and PCI information from the primary and secondary signal reporting. If you proceed to the “statistics” page you can select cellular and record the statistics there. See if there are packet errors or packet drops. If you have problems using cellmapper.net open a call with T-Mobile support and ask them point blank where is the tower my router is serviced by. They have the PCI information and can tell you the coordinates of the tower. You can use Google Earth and a drive about to confirm what you know and get a good ideal how to improve matters. Use your phone to locate the tower. If you use an iPhone put it into field test mode and read the PCI value it knows. Chances are both may use the same tower. It is not a given but a good datapoint. 

With the PCI information for the primary and secondary channels and the bands used you can use the information from cellmapper.net to determine where the tower is that sends to you. With this and some testing you may be able to better locate your router. Watch out for metal screens or buildings in the path to the tower. If a window has a screen that is metal either put the router above the screen or remove the screen from the window to prevent shielding of the signal. Don’t just rely upon the bars on the top of the router. They are actually rather generic as vendors don’t have a MUST directive for how to deal with those but a recommended use. One feature of the LED display on the top of the router is the alarms. If the router does have temperature issues it will or should report an over temp alarm. The only way I have seen to get the alarm is to use the LED display on top of the router. Forget the mobile application it is about as useful as well blah… It is very unreliable and not much value. 

If you only have say the 5G signal dropping from time to time it could well be T-Mobile engineers are working on the equipment on the tower in your area and that is the cause not the router itself. I highly suggest to not just accept mediocre service but talk with T-Mobile support engineers, try the router in different locations, get the information about the tower location and be patient. Record your findings from trying new locations and then dial it in. If you do the same thing, expect the same results. 

If I can help you understand what you see and help you dial it in I am happy to do so.

With the trees an external MIMO panel antenna might help out quite a bit. If you can get the n71 stronger sure that would make it more satisfying. Your router records B66 and n71 so the cell info in the second image with site 3154402 reports NB B71 but does not provide the PCI for 100% verification. I am not convinced that is quite the same. The n71 5G NR is an extension of the 600 MHz bands to enhance the 4G LTE by swapping out part of the banding to leverage the 5G. It depends upon the operation. If they are swapping 10 MHz of 4G for 30 MHz of 5G on n71 then that is where you would get a significant boost. To be 100% you really have to know the PCI of each band and identify the tower that has that PCI, physical cell ID. With the web version on my client at home using cellmapper.net I was able to get the low down on both the 4G and the 5G signals. The phone may not report or connect to the same towers as the router. It can be somewhat helpful but the PCI is important to have. Once you are 100% on the tower delivery to the router then you can really dial it in. An external antenna might help considerably but would have to be located properly to really make it rock and roll.

So that last Cellmapper picture from my phone that occasionally shows the red dot I was able to pull up on the Cellmapper website. When you click on the red dot, one of the PCI cells matches the PCI for my secondary connection on my trashcan (n71). Link Here

But with the first picture, the green dot closest to me does not show the same PCI for any of the cells for my secondary connection. Link Here

So I have one of two guesses. Either the first link is on the tower to the second link and just inappropriately placed. Or there’s a tower I’m missing when I drive by, perhaps on top of a building or something.

Seeing as though I live in the middle of nowhere in a rural farming area, I’m thankful to get what I currently can. The only wired option for me is Windstream which at most I can get is 10 down and 1 up.

I noticed on the Cellmapper app there’s an option to take pictures for the cell towers, I might try doing that because I have seen under the CellMapper reddit that a lot of people like to try and identify who and what is on each tower.

Anyways, I’m going to keep an eye out for the next time internet drops and I’ll update as I get more information. Thanks for your help Tinker, hopefully the techs are reading this and are able to get some kind of idea on what might be going on.

OK so that is helpful!

I can see the 5G NR n71 is delivered from the tower on the other side of town. That is where your router links to for the secondary channel.

See the screen shots attached. Both the 5G NR and 4G LTE towers are there. Close to one another but not from the same tower.

I have seen with my router when the secondary signal drops there will be a disruption for 2-3 minutes. The router does not handle the transition from 4G LTE to 5G NR well. That is my take. 

The change between 184 and 261 on the tower. Interesting. Notice the reported cell direction N 16 degrees and N 0 degrees. You need to look at your position in relation to that tower. Cell mapper reports three cells on that tower. The red dot suggest unverified tower. I have looked to try to find the tower on Google Earth via sat images but it is transparent or no image exist with it included. Probably more uploaded data would help solidify the GPS info on that tower.

It might be helpful to have a call with T-Mobile support and just bring that up. There could be work being done on the tower or there might be some issue with the equipment. If they dont get calls on a given tower I would guess they take it to be good to go.

You are lucky. My DL speeds are consistently below 10 Mb/s. I spent 3 hours today mostly on the phone installing a replacement gateway, switching out 3 SIM cards and 2 gateways. My LTE phone is consistently showing 18-30 Mb/s DL. I’m 1.5 Km from my assigned tower. Gateway has 4 bars of signal. Primary is 4 bars, secondary 3 bars.