Nintendo requires an Open Nat Type due to their games using a peer to peer network to connect consoles. Schools systems are likely to have a strict Nat Type, which would limit the connections available to the Nintendo Switch. An alternative is to set up a DMZ on the school network, and only allow Nintendo Switch consoles to connect.
Below are some additional connectivity troubleshooting tips:
NAT Rating Support
Resource provided by https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000PNVtCAO.
Ports can be TCP or UDP.
You can also use the router's DMZ. The DMZ of your network is able to open to the whole internet separately from your internal network.
As long as schools use the Nintendo Switch in the DMZ and not any actual computers, it won’t open vulnerabilities to the network.
Enabling Peer to Peer
For further support or information on Switch connectivity, the peer to peer feature allows you to directly communicate with other players.
Enabling peer to peer connectivity within the Firewall will allow access for your team's Nintendo switch.
Note: This entire list may not be needed, but has been seen to assist schools in connection concerns with Nintendo match issues.
V2.0 - 11/4/21 \\ Added Nintendo Domains list
V2.1 - 1/26/22 \\ Clarified additional steps for how to set up a router’s port
V2.2 - 9/22/22 \\Port updates-JM