WNDR4000 Router Login page connection refused
This problem is already solved, but i wanted to share anyway since there's one strange new observation.
Right after i reset the router (Firmware Version V184.108.40.206_9.1.89) from within the web-admin-panel with the reboot button (didn't do any firmware updates since quite some time and certainly not right before hitting that button), i couldn't connect again. Any attempts resulted in first showing me a page that says
You are currently logged in from another device. There can be only one device logged in at a time. If you log in from this device, the other device will be logged out. Do you want to proceed?
and after proceeding i get a connection refused status; from all the devices i tried with, even after shutting down one by one until there was only one left.
This seems to be not an unknown problem:
So after convincing myself that i really have to waste the time, i plugged all lan cables, turned off WIFI, connected a single pc via lan cable, did a factory reset and voila, i could login again with the default user/password combo.
Then i manually configured all settings again from memory. I started by using a different ip and dhcp range than i had before, applied, the router rebooted, everything was still fine. Then i changed to the exact same ip/subnet/dhcp-range settings as before and got the same strange multiple clients error message and the followup connection refused status like before.
Did a factory reset again, chose a different ip and dhcp-range, but still within the original subnet, rebooted a couple of times, reconnected all lan cables, configured and enabled wifi, rebooted all devices in the network and it still works.
Maybe a factory reset doesn't reset everything after all, that's the only explanation i've got so far.