Home internet modem keeps powering down and restarting

I'm in the exact same boat. Moved to the country where T-Mobile is the only provider with 5G about a month ago. Worked pretty dang good at first for how rural we are, but now the gateway keeps rebooting every 5 minutes or so maybe less. At this point it spends more time "powering on" than anything else. I work from home so I'm gonna need a fix asap 😫. Hotspot is only gonna get me so far… 

Same here.  We just switch over to T-Mobile 5g home internet about 3 weeks ago.  Worked great for the first week.   Then the second week, it dropped connection 3-4 times requiring unplugging and rebooting the gateway.   This week is the worst.   Now it cycles through shutting off then "powering up" about every 15 to 30 minutes.  And last night, I had to do the setup again in the Tmobile internet app.   This is simply not workable.   I'm not sure if this is regional, but I am in Central Arizona area.   

I already tried unplugging for 2 minutes and restarting (Tried this about about 15 times over the last 2 weeks).  I also restarted the modem from the tmobile internet app.  That is when the app no longer recognized my gateway and I had to go through setup again.    

Any fixes?   And please don't tell me it could be Tower upgrades/maintenance.  We need a real fix?   

I suggest to contact support or go to a local T-Mobile store and see if they can provide a replacement. Probably the power adapter. 

Thanks for this thread, I have only had the Sagemcom for less than a week and it suddenly started rebooting itself every 15-30 minutes based on the alerts I was getting off the firewall.  (Just note, I am still running dual WAN between Cable and T-Mobile Home Internet. So that's why I can still email myself alerts off the firewall.)

I decided to give it a whirl and switch out the stock power adapter to my Anker USB-C (up to 100 watts) adapter I use with my laptops. The stock one says it is 15 watts.  The cycle of rebooting for me stopped.  After a few hours, I switched it over to a leftover Chromebook USB-C wall adapter that is good for 45 watts.  No hiccups or issues after a few more hours that I've seen thus far.  

I’ll edit / post an update if anything else comes up, but the recommended solution definitely was worth a try for me. 

Um. I'm an electrical engineer. I troubleshoot hardware for a living, at least until recently when I retired.

Brand new T-Mobile Gateway, the tall, square in cross-section one. Started seeing $RANDOM dropouts, once every couple of hours, as soon as the thing was put in use.

On day, happened to be in the office upstairs where the thing was placed, down went the internet. Looked over, screen says, "Powering Up". There had been no power outages whatsoever. When it came back up, so did the internet.

Four hours later, lather, rinse, repeat. Called T-Mobile support. After the usual five minute wait, talked to a nice service rep.

Se said it was clearly a problem with the gateway. AND that that particular brand (the tall one) was known to have this problem. Drop shipped me a new one on a Friday, got it on this last Monday. Opened the box: Same rough shape (square in cross-section) but shorter than the original. Set it up. No more drop-outs.

Did have to swap the SIM card from the intermittent one to the new one, but that was it, beyond the usual setup follies.

Could be the power brick. But, speaking as a troubleshooter: I've seen hardware that does stuff like this. A fair number of reasons. Overtemperature on some device that causes excessive current draw; reset sensor whose voltage thresholds are too high/too low, so it causes a reset; bad parts in manufacturing that short out intermittently; and so on. I note that it took a while before it started doing this in my case, at least four or five hours. Most factories power up their equipment, sometimes in a heat tent, with the intent of detecting early failures. So this looks like a factory escapee: Should have been caught during testing, but worked long enough to ship.

There’s this general idea: One can do a mucho of testing when one builds a product. Testing the circuit board, lot testing individual components, testing the assembled board before putting it in the box, testing the complete box after assembly (functional test), and, of course, heat tank testing. If one is getting 99%+ yields at a particular test step and there's decent fault coverage, it's often cost-effective to skip some tests and use others. This works if one's suppliers provide low-fault batches of hardware; one pays more for that, but then gets to skip hiring people and mounting test stations, so it's an interesting balance for the manufacturing engineer.

But there are pointy-haired bosses who just love skipping testing steps in the interests of low costs.. and this smells of that.

Mine restarts daily, and has since we got the service a couple months ago.  Tmobile just sent a replacement 5g home internet router, but no replacement power adapter, and it's still doing it daily.  I highly doubt it's the power adapter since it's consistently once daily.  I'd say in my case this is more of a tmobile network issue than anything, and judging on the reports it's been affecting a lot of their customers, but rather than dig into the issue, it's simpler, but not cost effective, for them to just keep swapping out used equipment to all their customers.  I may just change isp's and be done with it than fight it.  

Same issue.. modem worked fine for a little over two months. Now restarts every 5 minutes or less disrupting service for about 3 minutes each time.. forget about using any streaming services…. local store (Collierville, TN) told me to kick rocks when I asked if I could exchange the gateway, sim, or power adapter. Said had to deal with corporate for all issues. I contacted support to request a replacement and was told they would call me in some days about sending one out… (why not order it then?)… I googled and saw that support is apparently encouraged to delay customers from calling back to protect the support staffs' performance stats… so I'm doubtful I'll be getting a replacement modem.. meantime I'm basically without service.  At this point I'm leaning towards canceling, then signing back up so I can get a fresh modem.. if I have issue with that I'll dump tmobile phone/internet and take my business elsewhere. It's nothing personal, I just need a service that works.. and I can't wait forever to get bad hardware replaced.  

I have not seen a conversations with that behavior. It sounds like the gateway has a problem or the power adapter for the gateway is failing. If you have only had it a few weeks I would ask to have a replacement. If there is a T-Mobile store close by that also supports the gateways I would contact them and see if they can do a swap out for you. 

Azzlyn2006 - I am just speculating but try reseating the SIM card. The SIM card holds significant information about the account and services. If the SIM is not making contact in the unit this could cause issues with the tower connection. If it is shutting down and then powering back up maybe it is a faulty gateway or power adapter. Before you do more or it goes down check notifications on the LED display. The Nokia receives notifications via the LED only, which is not ideal, but if the Arcadyan or Sagemcon are similar in this respect or not I do not know. If there are any notifications with error codes that would be something engineering should be able to work with. I do not believe the SIM connection would have any relationship to the unit rebooting. If there is a T-Mobile store that supports the gateways talk to them and see if you can get a replacement. I do not believe that is a tower issue. If a firmware upgrade was pushed to the gateway it might reboot to install it but now if it has an issue with the firmware or an upgrade went sideways that could possibly lead to it being in a bad state rebooting. Either way there is probably little you can do with it.