Can anyone who uses a Mikrotik visit this site? https://kmau.dealer-portal-ap.net/irj/portal
It works on every other router I have at every other location where I have a DSL line, but no Mikrotik configuration I can throw together will get it to come up.
I have a lot of mikrotik routers in our network (all of them are mikrotik) and I have no problems opening that page.
Works for me. Try lowering your MTU setting.
If your using the RB as a dns then check your UDP max packet size.