HI everybody,
I am having major difficulties with my DIR-655 router. I am using a VoIP hardware device (Fritz!Box FON) which for some strange reason will only work with firmware 1.11 (I tried both 1.20 and 1.21, both failed to work). With the 1.11 firmware, however, wireless networking only works occasionally - either the WLAN card (with a Ralink chipset) cannot establish any network connection, or do so only after at least 5 attempts, sometimes even more than 10. I have tried multiple operating systems, all have the same problem. With the newer firmwares the WLAN works flawlessly - but I cannot get the VoIP to work. I have enabled port forwarding (3478,3479,5060-5070,10000-30000,21,53,69,123) and have set UDP endpoint filtering to "Endpoint Independent" - this setting works under fw 1.11 but not under anything newer.
I have googled for this to no avail. Do you have any suggestion what I can do? I already contacted my VoIP provider and it is certainly a local router problem.

Thanks!
Edit: Also tried DMZ, turned SIP ALG off ... nothing.
Edit 2: OK - this is too weird: went back to 1.11 and WLAN seems to work for now... any suggestions as to what could be the problem with 1.21 though?