Where should I make a post about setting up a captive portal on a router I just obtained? It's not a fancy one that supports it by default. Any ideas?
I'm assuming it's a home router, right?
If so, then you should use http://superuser.com
From their FAQ:
It appears to be on-topic, and the users are fairly open to variation, and are not extremely quick to barrage with downvotes or closevotes as Serverfault may do.
for problems related to computer hardware and networking, super user is preferred.
Also have a look at all other sites of stack exchange network.
Maybe you could find a relevant one