There’s another well-known app for testing connection issues called PingPlotter. Blizzard doesn’t have documentation about it because they don’t use it in their forum troubleshooting, but that doesn’t mean you can’t try it on your own if the UI resets don’t work.
An explanation of the difference in testing clients:
WinMTR uses a type of packet called ICMP for testing with no other option. The trouble is that FiOS blocks ICMP requests on their network. ICMP is also the default option for PingPlotter, but you can choose to use UDP packets instead through the menu, which are less likely to be blocked. This setting can be accessed through Edit > Options > Default Settings > Engine > Packet type: UDP packets.
Please note: The UDP option is only available in the Professional version, which you get a free trial of for 14 days when installing.
In other words, if you want to dig deep into this on your own, PingPlotter may be able to help. Unfortunately, there’s no official support for deciphering the results here in the forum. However, you may not need help with it, or you have the option to reach out on a subReddit/FiOS forums for assistance.
Edit: I do think it’s worth exploring the UI changes/settings first. You may not need to learn the new app if it’s a problem with the local files. I hope this all helps 