After replacing my router I can not log into local home assistant

Hi,
After replacing my router I can not log into local home assistant. When I plug my old router back in it works fine. I can also log on to other devices localy with the new router but not HA. The other devices dont require a port though, Does this matter? I can log on through my duckdns but if i lose internet I cant log on. this also creates a problem with login into my deconz because it will only allow it through local conection. I have tried so many different settings on my router but can’t figure this out. im no expert at this though. Has anyone else had a similar problem?
My new router is TP Link AX5400.
I have spent way to many hours on this problem and cant figure it out. Any help would be greatly appreceated.

Thank you

It may be a silly question but did you check what is url of HA in your router ?

I have been using the ip adress with port number. I have assigned the ip adress in my router and set up port forwading for duck dns. but if i enter the ip address and port number on my local computer it wont connect.