according to our experiment the -udp switch works far better than -tcp, but YMMV. Apparently some ISP performs better than the others. Also switching to wired connection can help.

Here's how this works (as translated from the op. Credit wu360463231 in Steamcn forum):

The multiplayer is based on P2SP (peer to server and peer), in which players has to keep connections with other players and also Valve server.

There are Valve servers in Jiangsu, Hong Kong, Japan, Singapore, LA, and other regions. The server you connects to depends on the host. [...]

Error code 83: you are disconnected from Steam (Valve) service. (n.b. this is the case when you see bunch of Steam popups that your friends "started" playing games at once)

Error code 5038f: P2P host are d/c or is experiencing interruptions

If the host are d/c, all members in his/her server will be d/c and see 5038f error.

Solution: force Steam to use older Friends UI, which is based on an older protocol rather than WebSocket found in the new UI.

Hope this works for you.

Source: https://www.reddit.com/r/MonsterHunter/comments/96h8w5/a_potential_solution_for_constant_disconnections/