I have no forwarding rules set up. When I try to add my first rule for a specific client on my LAN, I get an error message telling me the IP is already in use. I have tried rebooting my Deco, to no luck. I have tried different ports as well, just to test it. This is frustrating, has anyone had similar issues? I do not want to do a factory reset, as I have many DHCP reservations and other settings that I rely on.

I've had forwarding rules before, which have worked just fine, also for the IP I'm trying to use now. Yes, I have deleted all rules relating to this IP before trying to setup a new rule. The list of forwarding rules is empty.

I am using this IP as a DNS server I the dhcp settings, which is the only thing I can think of, but that shouldn't be a conflict for port forwarding anyway.