Some weirdly specific issues with internet connection in games

I have been doing online gaming with friends and this has been a problem for a while but it is starting to be more severe lately. I think I can kinda guess the issues and will be talking to ISP later but right now I'm not really sure what to call it.

Problems:

in PEAK , I always randomly disconnected from the voice lobby (but the game lobby is still fine). So my group installed the mods to keep track of the voice lobby connection. It works fine at first until the voice lobby IP address changes, which migrate all the clients to another IP including mine. The problem is that the game failed to connect to that specific IP repeatedly which resulted in me being isolated from the rest.

in Helldivers 2, I tried to connect to a friend lobby but my game crashed every time I do that. He tried to connect to me, my game crash as well. *(Helldivers 2 uses nProtect and as far as I have speculated, a disrupted or force closed connection will likely result in the anti cheat freaking out and instantly terminate the game)*. I joined a random public lobby and he joined me later, my game still crashed. Weird thing is, after an hour, we can join each other with no problems at all.

(This also happens to another random in my lobby today too)

in Deep Rock Galactic, I simply cannot connect to the game server. Most of the online system (like quest and public lobbies) are unavailable. Although, I can still verify my mods and connect to the mods server that is built-in inside the game. I'm also able to join a friend lobby (via steam). Only the connection to the main server is unavailable.

I'm not sure how to describe these issues to my ISP so I'm asking here for someone to explain or summarize the problems for me (Doesn't need to be accurate, I will just tell them my guesses)