How do I stay on n41 band on my trash can?

The battery might, I say might, keep the cellular signal alive but if power goes out the wireless radios will for sure be taken down. Mine seems to behave as if there is a soft reset when the cellular signal falls. Once it is established again there is a delay prior to full communication is established. I keep mine on an APC 1500 UPS to keep it standing and filter any transient spikes that might ride the AC line. When I lived in CA we had PG&E and the power was so flakey I had a PC motherboard spiked and destroyed some time ago. After that I put all our electronic equipment on UPS systems. I still run three UPS systems here in TN. 

I am not so sure that T-Mobile doesn't push software to the router when it has a new release. A support engineer told me when the router reboots it will take an update if available. From that I suspect they push the software updates with management software and if the router reboots then the new software load will be installed. I have been on several revisions of the software. A couple of weeks ago the 1.2103.00.0338 was installed on it. I discovered an authentication bug. I know beyond a shadow of a doubt that it is due to the router software as I had never seen the behavior before that was running. It is easy to trigger and I have tested and confirmed it with multiple browsers on Apple, Windows 10, and Linux Mint and Garuda Linux. The only way to avoid it is to not save or autofill credentials from the router web interface. If you do encounter it I did put a post up about it a few weeks ago. T-Mobile support said they would follow up with me on it but they never did. I am 100% sure the issue is with the 1.2103.00.0338 and the web interface. The values that will "change", be inserted into the auto save window can ONLY come from the router. Just don't save your "admin" authentication to the browser and it should be ok. If you do encounter it look at your passwords in the browser, remove the one saved, and restart the browser. Then authenticate with your last functional password for the admin account. If the browser pops the question to save the authentication, just say no. Better yet don't give it the chance to go there.