TMobile Gateway IP Addresses

  • 12 February 2022
  • 17 replies


Thought I’d give the T-Mobile internet a try but am concerned about it’s use of IP addresses.

I see the address of the gateway is

Does that mean all my devices would have to be changed from my current 192.168.1.xx 

to the new 192.168.12.xx address?

If so it’s a deal breaker for me. That and not being able to port forward ends it.



17 replies

If you connect your devices to the gateway, either Wifi or ethernet they will receive 168.12. addresses. If you choose to add a router you can retain 168.1 addressing scheme for all devices connected to the router. 


Seems a ridiculous solution and one I would have no idea how to use or setup.

There’s no way to change the gateways address?

Nope, can’t change it.


Shouldn’t be sold as home internet…it’s just a hot spot.

This is an incredible case of consumer fraud.  As the user above stated, this is essentially a hot spot, and the IP addresses that are connected to TMobile’s server(s) are frequently blocked by Cloudmark.  After spending 3 hours!!!! on the phone with various clueless TMobile reps, i was ultimately told that the IP address the gateway (or whatever) generates cannot be changed and TMobile is doing nothing to resolve the fact that these IP addresses are being blocked.  ANYONE WHO STUBLES UPON THIS POST:  DO NOT TRY THE TMOBILE 5G INTERNET SOLUTION IF YOU WANT TO STILL BE ABLE TO ACTUALLY SEND OUT EMAILS!!!

Userlevel 7
Badge +8

The T-Mobile gateways do have a DHCP server which is set with the fixed gateway IP of and the network mask of /24 for the Class C, IP network. The DHCP scope appears to be from 101-254 and the gateway address is excluded. Some users do connect an additional wireless router and double NAT just to have additional local network controls and features. Devices that do connect to the wireless or Ethernet network directly via the available gateway resource are restricted to the 192.168.12.X/24 network. There are workarounds for ways of communicating across the 464XLAT environment but of course it all comes with a cost. 

T-Mobile does run 464XLAT and they leverage IPv4 and IPv6 so there are some limitations for port forwarding with the technology. It is a move toward support for IPv6 and migration as IPv4 addresses are in short supply now and the cost to obtain IPv4 addresses is prohibitive. The use of IPv6 provides the enormous pool of available addresses and given the explosion of internet connected devices moving forward with IPv6 is really the most cost effective solution. As more hardware and software developers provide IPv6 vs IPv4 for content delivery many limitations imposed by the prior paradigm for IP communication could be resolved. It will be years before the industry moves forward with applications that embrace the future requirements. It is pretty much like people still having ICE vehicles due to the infrastructure and the cost of electrification of vehicles and the enormous costs associated with making the move to build out support infrastructure to make it happen. Cost is a big factor period.

User email in/out from the local LAN works. If there is content filtering taking place then that is a different issue. I have used Windows, Apple, and Linux clients for email service/delivery and it seems to work fine for me. 

T-Mobile has pushed to be innovative and push forward with the 5G cellular internet delivery. They provide the service at a lesser cost than “some” big ISPs and do it without contracts, extra hidden fees, and they don’t even force the new subscriber to buy the gateway nor add hidden connection fees and etc… plus the cost is not going up every year or at a renewal period. Is it perfect? No. In some environments the delivery is very good. Cellular communication has some limitations for some locations as there are many external factors to contend with. I don’t work for T-Mobile. I am just a user since January 2021 and I have seen some glitches here and there but service from the 5G cellular solution with T-Mobile is much faster and more reliable than the provider we had using DSL which was more expensive and much, much lower bandwidth. If the T-Mobile cellular solution does not fit for you go find internet nirvana and be happy. Life is short.

I have had T-Mobile for 6-8 months now and have had no issues with email. Have you tried contacting Cloudmark via their CSI IP Reputation Remediation Portal?

Userlevel 7
Badge +8

So according to Cloudmark:

“Far and away the most common cause of Cloudmark filtering issues we see here at SocketLabs is the result of an Exchange server user becoming compromised. We have often seen new clients interested in using our services due to their person to person mail being diverted to the spam folder. What they didn’t realize is that a compromised account was spewing thousands of spam messages a day. This resulted in many user complaints and Cloudmark spam trap hits. While the SocketLabs platform can help detect this type of issue quickly, often times the damage has already been done.”

Checking with Cloudmark to confirm the fingerprints for your email accounts is a good idea.

Userlevel 7
Badge +8

The socket labs site has good info on Cloudmark and there is a link in the article to get the free desktop tool for checking the email client for matching fingerprints. Cloudmark Desktop One

If the emails appear to be blacklisted it is possible they are. There is a listing of service providers in the document that covers those who use Cloudmark technology. 


We did contact Cloudmark.  So far no response or change.

iTinkeralot:  We use some Gmaill accounts and some hosted by one hosting company.  I do not think we even have any Exchange servers.  All I know is that the Cloudmark blocking messages ALL list the TMobile ISP. Not my area of expertise, but the only thing that changed a day or a day and half before getting all these rejection notices was switching to TMobile.


Userlevel 7
Badge +8

That is really curious. Since using the T-Mobile gateway solution here I have been using the same Gmail account and the same iCloud account. I still have a Microsoft account, mainly for the Xbox and my wife’s and son’s clients and all the have worked just the same as ever. I run Apple, Linux and have Microsoft clients on the LAN and we have had no issues with email blocking. I run the BitDefender security suite and have done so for going on 8 years or so. Did you run the CloudMark Desktop tool to test for a possible Cloudmark fingerprint issue?

I really don’t know what else to suggest. I have not seen other postings reporting such a problem. I have been watching the community threads since early in 2021 and I just do not recall seeing an email blocking issue like this. 

not sure precisely which tool to use at that page…..

Userlevel 7
Badge +8

ah ha!

All I had to do was go there and search for Cloudmark Desktop then go to the link on the page that renders and advertises the 1.2 application. Probably moved the link to the application.

Userlevel 7
Badge +8

Given the dates on things I am not sure about that application. Read through that before you take it too far. I am just not sure about that tool and what it does for sure. It is compatible with Outlook 64 bit from the description. I have found some plug ins for Outlook can be a bit problematic. Maybe asking a support question and just see if they will respond and possibly they can provide some insight.

Sorry I did not research it to the end. I was searching looking for answers and that article seemed to provide good pointers and information. I am not sure that is the right tool or what all it contains. 

Userlevel 7
Badge +8

That SocketLabs article is from 2014 so I have to wonder about that. I can see what they are referring to with the signatures on messages but the date of the article and the application of the utility are both a bit dated. Not sure this is not just a rabbit hole. 

Well, last post on this.... switched back to a cable isp and no blocks of any kind.   Don't need to be a tech genius to deduce that tmobile was the culprit.  At least a dozen hours speaking to various tmobile techs and not one could help... in the end, just told, " sorry, we cannot help." Even cancelling and returning the gateway was a totally frustrating experience, but thankfully this experience is over.