While I think the Fritz Box is a pretty good piece of hardware, the internal lan configuration absolutely drives me insane and never seems to work for me properly.  I know there were bugs in old versions of the firmware regarding assigning fixed IP addresses, but now I'm having a massive headache trying to setup port forwards in the permit access section.

No matter what I try I keep getting:

A device with this name has already been configured

As best I can tell, it's using the the network name/id as an index for the port forwards and once you to try to setup a port forward to a specific windows 10 machine on the FritzBox 7490 it locks it up and you can't add other port forwards?

I'm running the 7.10 firmware so I'm at the latest revision.

In this particular case, I managed to finally force it to accept a port forward by manually configuring it against and IP address rather than selecting it from the dropdown list, but I wanted to add a secondary port forward as I'm trying to expose several different services on this one windows 10 machine to the internet.  So I hoped that I could just add a new share to that one device that is already working in the Permit Access section but I get that same error again.

I have other machines on the network setup in the exact same fashion, but, admittedly that was done last year when the Fritz firmware was at an earlier revision.  So I suspect this is a new bug.  It's a bit of a nightmare trying to get support from the internet though as most published pages for the fritz box on google are from German forums so it becomes really hard to seek support from other users to see what they are all doing.

Anyone here have this issue and any suggestions on fixing it?