This site can't be reached

As I type half of the sites I’m attempting to visit using the Tmobile 5G internet router do not work. There is a workaround to this issue. We had a similar issue with ATT almost a decade ago that blocked out access to viewing and downloading movies on our PS3. Old skool refers to the solution as running your modem in DMZ mode.

For household modems it simply means you run a hard cable out of the Tmobile 5G modem and into your old modem that worked before. The Tmobile 5G modem will pull the signal out of the sky except your old modem will broadcast it via Wifi instead of the troublesome Tmobile modem. 

We didn’t have an old modem, but I read that Apple Air / AirPort modems were friendly with this set up. I purchased the Apple Airport A1521 Airport extreme almost 10 years ago for $100. They last and they're tough. Look online and you can get them for $25-$40 preloved. You do not have to have an Apple phone or device to use it. After I ran the Tmobile 5G through the Apple modem DMZ style, all is fixed.

Have you tried a different browser?

In general, the problem may happens for failing on DNS lookup . DNS is that network address that translates the website name to its internet address. Most often it causes for not getting the internet connection or misconfigured internet or network settings. Another reason could be the firewall preventing Google Chrome to load the webpage. In most cases  Flush Your DNS Cache is solve this problem:

Once the command is executed, OSX will prompt for the administrator password as confirmation to proceed. Also, here are some other possible solutions for these solutions will try to minimize or remove the error completely and takes you to your desired website in your Chrome browser.

• Restart Your Internet Connection
• Clear browser cache, history and cookies
• Reset Chrome browser settings
• Reset Wi-Fi Modem
• Restart DNS client
• Change IPv4 DNS Address
• Reset the Chrome profile Sync
• Remove browser extension from Chrome

Seems to be working fine for me in Edge.  

certain sites I get "page cannot be found"" in t-mobile network.   But if i turn on VPN, they magically can be found.   there are a lot of quirks that i have had with this t-mobile internet/network that i didn't have with my previous provider, ie page can't be found for certain sites, printer can't be found over the wireless.   Use VPN service for these troublesome sites, and plug in your printer via ethernet and hit it via IP address are my workarounds for t-mobile.