Strange. In my experience, I've been using Virtualbox with an XP VM, and I have my primary connection with an empty secondary DNS field. That's what gets my DS online, along with disabling the firewall for the dongle.
Maybe you could try that.
I am trying to hack Fire Emblem Warriors on my 2DS XL, I have been trying to get it to work, but I need some extra help figuring it out. I have HEX codes, and a possibly outdated plugin, but I dont know how to implement them