This is a guide on how to fix the error "Unable to connect to realm list server."
All you have to do is open up your logon config and change:
<Realm1 Name = "Name"
Address = "DNS HOST:8129"
Icon = "PVP"
Population = "1.0"
TimeZone = "1">
to
<Realm1 Name = "NAME"
Address = "DNS HOST:8129"
Icon = "PVP"
Population = "1.0"
TimeZone = "1">
<Realm2 Name = "NAME"
Address = "WAN IP:8129"
Icon = "PVP"
Population = "1.0"
TimeZone = "1">
and also change the realm count to 2:
<LogonServer Address = "127.0.0.1"
Port = "8093"
Name = "Default Logon"
RealmCount = "2">
I hope this has helped some of you secondary computer users on how you can connect from the same router, and don't forget to use your Wan Ip as the realmlist for your secondary computer.