Topic: Internet (NAT) issues since 19.0 update

Anyone else having problems with NAT types and connecting to other players online since the 19.0 update?

I have an OLED switch, and I've had no issues on my wifi before then. I had the same setup this entire time and had no issues ever. Then the day it updated, I hopped back on and was unable to connect to a room on 3d World or a regional match on MK8 or anything. eshop works, but online multiplayer doesn't. it has been giving me Error Code 2816-051X every time, but my NAT type is often B and hasn't been an issue until now. Furthermore, I tried a lot of other connections: wired on a different network (80mbps up/down speed), my friend's speedy wifi, a personal hotspot even... but I've not had any luck.

Port Forwarding isn't an option with any of these, and I tried the DNS trick where you change it to a manual 8.8.8.8, but to no avail.

Can anyone relate or has any idea of what I could do to solve this?