Every so often port forwarding stops working and the only solution is to reboot the router. I can't even access the login page at port 8081 but can see my server on port 80. Everything works perfectly when I reboot.

Not sure on the problem, but you can set a scheduled reboot as a temporary fix.

when updated firmware did you used the *rst* file extention & all setting back from the begin or just updated with the *all* & with current settings?
Also is the latest firmware or older?

Don't know what version I used but I have the latest version. I have set up the syslog to see what is happening and of course it has run perfectly for the last 37 hours.