There are 5 parts to a connection:
1. Your phone
2. Your phone's connection to the internet
3. The internet (the path between you and the server you're connecting to)
4. The server's (that you're connecting to) connection to the internet
5. The server you're connecting to.
Evidently 1 and 2 are okay, so it's probably 3, 4 or 5. And there's nothing you, or anyone else, can do about 3 or 4. 5 can be fixed by the people who run the server.