Might bump this, see if we've accumulated any other Switch owners on here in the past year! The online service is getting pretty mixed reviews at the moment, but Nintendo just announced quite a few really promising games, including a new Luigi's Mansion and ANIMAL CROSSING… finally! Both coming out next year. Between those, Fire Emblem, Yoshi's Crafted World and Daemon x Machina, 2019 is looking really good.

Apparently I had port forwarding set up correctly except for not having a static IP address. I've done that now and the problem seems to have resolved itself.