Are you trying to with a friend, or are you just trying to get the main menu to load ?
The developers of Feed and Grow Fish have noticed the rise of the Facilitator meta. In recent roadmaps, they have hinted at coming to the main menu. This includes: Feed And Grow Fish Connecting To Facilitator
is a well-known issue indicating that the game's multiplayer servers are unreachable or the matchmaking service (the "Facilitator") is down . Current Status of Multiplayer Are you trying to with a friend, or
Sometimes your computer holds onto old network data that is no longer valid, causing the connection to the facilitator to time out. This includes: is a well-known issue indicating that
If the above steps fail, you may have a "Strict NAT" type. This means your router is refusing unsolicited incoming connections. To fix this, you may need to forward ports specifically for Steam.