I've got a problem with connecting to other consoles on my Switch and PS4. Both of my consoles have strict nat types and I've tried everything possible to try and fix it. I've tried portforwarding, turning off UPnP and manually adding ports through portforwarding, I've tried putting IPs into DMZ, none of them works for some reason. I dont know a lot about routers so I'm not too sure if the issue is my router or my ISP.
Are there other ways I could try to fix my strict nat types on all my consoles?
Note that Multiplayer games work like BOPSIII, Tetris 99, but when it comes to trying to connect to a private party or private game, it's impossible.
Mariokart on the switch does not work, Smash Bros Ultimate doesn't work. Please help, I really want to fix this.
UPnP is currently on, and doesn't let me connect to private games. I've got static IPs for my consoles as well.