Good afternoon OdoriTsuki and thank you for posting on the Final Fantasy XIV Technical Support Forums.

If it works fine with your phone's connection, then you may be having some issue with your mainline connection. Likely, you are running into a difficult area along your route to the servers, which might explain why you don't run into issues with other games (those would take you along a different route to a different server). Have you contacted your ISP about this issue?

I do have a few questions about your disconnections, however:

When did this start happening? Did anything update/change on your PC that coincides with this?

Where in-game does this happen? Do you notice a pattern (Only in combat, only when teleporting, etc.)?

We hope we can be of assistance in helping you enjoy the exciting world of Final Fantasy XIV!