Platform: Windows 11, prebuilt Direwolf 1.8 binary (direwolf-1.8.0-390d4a8_x86_64.zip).
Winlink Express uses port 8001 for its HTTP forms server.
Direwolf is launched using a packet session with KISSPORT is set to 8100. Notice that when Direwolf starts up, it says it's listening on port 8001 (default) as well as 8100.
Open a new Winlink message and try to use a form, Winlink complains that port 8001 is being used.
Workaround
Set KISSPORT 0 first before resetting KISSPORT 8100. This seems to stop Direwolf 1.8 listening on port 8001.
I haven't tested this on prior versions so I do not know if this issue happened prior to version 1.8.