Sorry to revive an old thread, but I just ran into a similar issue with my Petsafe feeder. For me I get the slow blue flash that indicates it’s connected (as the router shows as well), but it thinks it has no internet access. I have the AX86U, but wondering if there’s something about the ASUS...
I just got the XPS 15 with this Dell DW1830 card. I can't find any info on what exactly it supports though, beyond 3x3. I do take it that 3x3 means it won't support AC2400, but I'd really like to know whether or not it supports MU-MIMO. Not sure if there's a way to test for that.