This problem happened to me too and I run mtadiag and it fetched this
This problem occurs when I want to go with Wi-Fi, but I when i am trying join a server with other internet it can join but with my WiFi I cant join a server
This problem happened once and I plugged the modem in another place and the problem was solved, but now it doesn't work.https://imgur.com/a/h5uvW0D