I switched to T-Mobile ISP a week back and only reason for that was couple of pretty good offers. From the time I switched I honestly was regretting as I was facing DNS issues with a few websites and sometimes my work VPN too. It will not be able to reach a few websites for a few minutes and then it would just work like nothing happened. Initially I could not understand what can cause this but then it occurred to me that it must be DNS issue. To my horror, I realized that DNS (and in fact even many basic settings) can not be configured on this T-Mobile gateway. I was facing this issue on a macbook, everything else just worked fine so I then thought of seeing what my macbook was using. It showed local network configured as DNS server, I removed that and added cloudflare’s DNS 1.1.1.1. That has fixed my problem.
In short: If you are facing trouble in reaching some websites periodically and this is happening only on a few devices then try switching DNS on your device to 1.1.1.1 or some other open DNS servers.
