forwarding port 3659 UDP on the sagem ADSL router?

[#1]

i am finding that the port forwarding interface is very buggy for this router. when i go to forward port 3659 UDP for an online game i see:
Add virtual server named battlefield 4 failed. Status: Duplicate Entry protocol:2,EPS:3659,EPE:3659,IPS:3659,IPE:3659, it has been used.
i have no idea what this message means. there is no other port forwarding rule that uses this port as far as i can see - either in the pre-existing rules or even in the unused templates.
anyone know how to resolve this? thanks

[#2]

I've also encountered this error when setting up a custom rule. I think it's broken. If I don't specify a "to" port, it complains that both start and end ports are needed, so it's not an issue with duplicate ports in the rule.
Also, once you make a custom rule, there's no way to delete it! There's not even any way to accomplish a port forward via the expert_user.html method, only a port trigger.

[#3]

I am also encountering a similar issue. I created a custom rule and assigned it to a device, decided to edit the rule, but now it has disappeared from the assigned rules list.
Now if I try to apply a new rule to a device using the same port(s), I receive the duplicate error.
Rubbish!

[#4]

I am also having problems with port forwarding. In summary, it's rubbish. In the past it has worked for a short while and then broken. Setting it up again makes it work for a short while again but soon the setting are lost and it needs to be done all over again. To make matters even more frustrating, it is impossible to edit an existing setting and trying to create a new variant results in a duplicate error. The only thing I have found you can do is to wait long enough until the router loses your existing setting before creating a new one. So basically you are relying on one bug to help you overcome another bug. It's shockingly badly implemented at a user interaction level. Probably not a lot better behind the scenes either because correct settings only last a short period before being lost. The cherry on the top is that even the expert page doesn't give access to port forwarding so the router is useless in that regard.