Nintendo Switch online gaming connection error

[Nowen]

I cannot get the online gaming portion to work on my Nintendo Switch.  I can get on the eshop just fine & internet / wifi works on every single other device in the house, so it's not a bad router or something.  When I test my network connection the NAT is scored 'D' which apparently means it will be difficult to connect for online gaming. (Read: pretty much impossible)

My spouse works on the security side of IT and my assumption is that our network has been secured to the point that the switch times out when trying to connect.  I've found the troubleshooting page on Nintendo's site, but there are several disclaimers on the page that basically say it's up to the user to determine their own security needs. 

So here's my question - are the settings Nintendo recommends inherently insecure in some way, and if so, is there a way to secure it that my switch will still accept?