If it supports UPnP why do the docs not say: turn on UPnP? If you search for UPnP in the docs, you get exactly zero results back.

I don't think anybody here (including me) claims these are _good_ docs.

Is there any evidence that the Switch supports UPnP? Because some quick googling did not suggest it does.

My router has never seen the switch use upnp.

IMO, because they're trying to keep it simple.

Most readers of HN will understand (or at least understand the goal of) the checklist for debugging network issues.

Skipping straight to Port Forwarding eliminates any issues on whether UPnP is actually working correctly. Growing up, some of my friends had routers struggled to handle UPnP correctly. If I knew they were the only one needing port forwarding, I'd simply turn that on for them instead of trying to figure out if UPnP was actually working correctly.

> not actually knowing what ports third party switch software

more than likely i'd think this is for enabling inbound responses to outbound ephemeral ports given the port range

Even a restricted NAT should allow for this without explicit port forwarding configuration?

Unless you're doing something like active FTP where it's replying to a different port than the one the request originated from. Which would be a interesting choice for a console designed in like 2018.

It’s a firewall thing not a batting thing. You need a stateful firewall to do that kind of smart port forwarding. Which, to be fair, all consumer routers should have.

Stateless firewalls, however, need to have explicit rules for UDP traffic. So that’s what Nintendo are addressing here.

NAT functionality especially for UDP can be incredibly flaky in a lot of consumer hardware, mangling payloads, randomly dropping associations or having extremely short timeouts, and other plain buggy behaviour.

I think even their first-party games use random ports.