Why do my SharePoint links and files not open? (on T-Mobile 5G Home Internet)

Could be in the security of the MS applications? MS apps may not like the IP changing rapidly. As noted on other threads T-M flips the IP's really fast, that kicks people off of their web pages and apps. No use calling T-M support as you will end up offshore with someone that has no clue because it's not in their book of answers. I worked my way to a USA Tech in Albuquerque (T-M Headquarters). That helped answer a few questions I had, not on this issue. At least I could understand him, and he wasn't just reading from a book of answers.

If you’re using a VPN, MS apps can get confused and drop you thinking you are in Costa Rica, then Canada etc, when it knows you’re in say Los Angeles.

JMHO on all of this.