When I play Pokken DX on my home university network, it takes a long time (>10 minutes) to be matched with another player, and I frequently experience error code 2618-0513 ("NAT Traversal Process has Failed").
However, if I try playing on a non-university network, such as my phone's personal hotspot or hotel wi-fi, I get matched up with players in seconds, and I never experience that error code. Additionally, I have no issues with the store or other online functionalities.
I have run the connection test, and it says that my NAT type is B, with up/down speeds greater than 3 mb/s. Switching between wired and wireless connections doesn't make a difference.
How do I improve my network connectivity on my university network?
You need a public IP address, not a private one.
The problem has to do with the specific NAT that your university might use. This answer is specific to my university, but hopefully it's useful to others.
When you register your Switch on your university's network, there will likely be some firewall settings to choose from. You need to set your Switch's settings to that of a server, so that it can accept P2P connections. Additionally, you need to ensure that your Switch has a public IP address, not a private one. In my case, private IPs use NAT, whereas public ones do not.
After I changed my Switch's IP address to a public one, the connection test said that my NAT type is now A, and I am matched up with players as quickly as I am on other networks.