Hub Zero Porforwarding bug

[#1]

Hi I'm forwarding several TCP ports to a device connected to the router via ethernet, the device is configured with a static IP address and i also have a static external address.
I create a new 'Game or application', it appears in the dropdown list. I select it and select the correct mac address from the 'Assigned to' dropdown list and click add to complete the process. Once added the ports are opened, and all is well, for about an hour.
After a period of time the forwarded ports are no longer open and the forwarded service stops responding. A port scan on the ext ip reveals the forwarded ports as 'Closed' and all other ports as 'Filtered'.
When checking the web UI the created 'Game or Application' is now no longer available from the dropdown list. Although it is still in the table containing the currently forwarded games / applications.
At this point if you create a new Game\APP and forward it all over again it will work but only for a short period. I've factory reset the router and started again, still nothing. I am also forwarding a generic Game/APP which already exists in the list and this also has the same issue.

[#2]

Bump

[#3]

Bumping isn't allowed on this forum you'll have a Mod after you   although I'm surprised no-one has posted for you, but it might be better if the post was on the Hardware board anyway (a Mod may move it).
I can't answer your query directly at the moment, but see if any information in this thread http://community.plus.net/forum/index.php/topic,136822.0.html is of any help and points you in the right direction.

[#4]

BUMP!!!!!!!!!!!!! 
Thanks Anotherone
I now have 5 Plusnet connections and all their 'Hub Zero's have had the same problem, so far I've had to go out and buy 'proper' routers to resolve this issue.
This looks like a firmware bug if i've ever seen one.

[#5]

I guess my main question here is as the help desk don't support their own routers will any one ever care about this problem and try and do something about it or am i just wasting my time here?

[#6]

How is the device given its static IP address? Is it always assigned the same one by DHCP from the router, or is it set manually on the device itself? Is the device listed as "Unknown" in the router or has the router discovered its name? I think there's a known problem with forwarding to devices the router labels as "Unknown", when there are multiple "Unknown" devices, the port forwarding may get mixed up and end up going to another of those devices.
Also here: https://community.plus.net/forum/index.php/topic,138269.0.html