2.4 Ghz internet devices keep disconnecting from GSE internet box

I like all these steps.  Unfortunately it is nothing new that we already tried on my first call to tmobile support.  Which ended in getting a new modem shipped out even though the one I had was only a week old. The issues started after a forced firmware update or that is my suspicion. 

So far multiple factory reset.  Sim exchange. Always breaking up the network into multiple separate bands and dumb down the security protocol.  Daily restart of the new replacement modem because the tmobile internet app itself won't even work unless you frequently restart it. All 4 bands sit up as you described with one that is combo of 5 and 2.4 ghz (default from the box), one only 5 ghz, one 2.4 ghz dedicated with the WPA 2 protocol and one 2.4 ghz only with the WPA 3 security.  Unfortunately 4 is the max these router will support.  I have trimmed back to 3 and even 2 bands only in case I was overwhelming the router but that didn't help either.  Even as I wrote this help request up last night I went down the hallway and noticed my thermostat was no longer online (yellow exclamation mark across the wifi symbol, usually means signal is reaching it but the password couldn't be negotiated). 

My home isn't big so from the router to the furthest device (smart TV) the signal strength is 80 percent on 5 ghz and 100 percent on 2.4 ghz (because like you said, 2.5 travels further than 5 ghz) and is about 30 feet away from the router.  The router itself is speed ping test at around 216 to 250 Meg down load and between 116 to 140 up so it's able to handle multiple streams without lag. (I have recently added an external antenna to get those speeds and was hoping that would make a difference in problem even though it shouldn't and it didn't). Problem still exists regardless of internal built-in antenna or the external antenna. 

My biggest clue so far is how the printer was assigned the wrong default gateway or other times the wrong subnet mask when connected via Wi-Fi. Other devices are not able to provide that information to me but the printer has a  trouble shooting page that prints the network status in all the details.  Since this is assigned by the router DCHP function it seems the issue originates there.  Here's another anomaly that happened on both routers so far.  The LG fridge shows as being connected to the network but without the Wi-Fi symbol which usually means the device is connected via ethernet cable. (Amazingly sometimes it does have the wifi symbol but regardless of the presence or absence of the symbol I still only manage to have a  connected device for just a few hours before it looses internet functionality) 

A new puppy is what caused all the problems as she dug up the cable connecting my house to the Comcast line pole so I figured I would give a wireless router a try. Since I am in a wheelchair it would be hard to dig a new trench in the yard and encase the wire inside piping that she couldn't chew through. I even would have to go under a small area that has been covered by concrete so that's why I left Comcast. It is not impossible though I would like that as a last resort answer. 

Please let me know of any other ideas I didn't mention as trying already. And thanks for your thorough explanation of the steps suggested 

Norman 

Been busy but I have an update on this issue.  The computer connected to 5 gigahertz bandwidth has been more stable for a week now.  It was like a whole week that we woke up and still had internet service throughout the house.  Less of the devices that connect only to the 2.4 gigahertz bandwidth were being dropped. By George, maybe the issue with the gateway has improved.  Not so much today.  Today all the devices that are connected to the dedicated 2.4 network are being randomly disconnected from wifi.  My home thermometer won't stay connected more than a couple hours at a time.  Just like the fridge. But here's what I have discovered because of getting a new internet capable home security system. The gateway is having trouble with the password working. Here's what's up. The device will no longer show online and trying to reconnect prompts for the password every time. When it goes to the handshake stage of connecting the error message of incorrect password happens. It's the same password I have been using for a decade. Trying to verify the password on the tmobile internet app gives that oh so common error message The gateway did not respond. If you're seeing this message repeatedly, try restarting your gateway.  You know restart the gateway only resolves the error message at a one in six chance (means you sometimes have to restart 5 or 6 times before you can get past the message). So I  noticed the plus sign was available to click on.  Just for laughs (why not when the problem continues to be extremely frustrating) I clicked on the plus.  Should not have let me do anything since I already had 4 named networks which is the limit for this model gateway. Instead it allows me to go through the steps and supposedly create another named network and take the 90 seconds to automatically reboot.  When it's back up the newly created network isn't there but the 4 that were now show up and clicking on the plus immediately gives the message you can only have max of 4 networks. 

So to sum it up.  The gateway fails to recognize the password intermittently resulting in devices being disconnected from the wifi.  Second it fails to recognize the networks that it's supposed to be broadcasting. This leads me back to my original thought that the gateway is having either firmware or software issues.  But if anyone else has any ideas please let me know and I'll be happy to try them. I am disabled now but I was going for a degree in IT before the company I worked for transferred all those jobs over seas so I am willing and capable to try very complicated procedures to fix this. Provided I can execute those commands with this crippled interface (you can't even see logs)

Thanks 

DaFattMann 

hmm. Figured I'd try to add some scren captures 

Sorry for being away from this topic but I have spent a lot of time in the hospital.  Things are going better now as to I have been able to return home.  Enough of that. 

Great  news! I have a permanent solution for the problem with now the third? Fourth? Gateway customer service has sent trying to fix the issue of not staying connected to wifi. It was to invest in a cheap wifi router. In this case the TP-Link C24 iunder 30 dollars at Walmart. I connected it to the otmobile Gateway and created a 2.4 gigahertz network and have all the home appliances, printers, alexa devices, thermostats and any other device that I restricted to the older technology.  Not a  single dropped issue since then.  I used the 5 gigahertz network for the home security system and tablets and computers.  The only devices that are still using the tmobile gateway is the son's gaming system and the smart TVs. When they loose connection or slow down simply restart those to get them reconnected to the wifi. 

This,to me,is proof these new 5G gateways are a POS.  But at least you can fix the problem and end this frustration. Best of luck to all those who helped or need this solution. I can now once again tell the refrigerator to make more ice or preheated the oven before I get home or control the temperature and lights in the house.  Yay! Now I can smile and save money.