Last Thursday I upgraded my router from beta 52 to beta 54. Shortly thereafter, I updated my PBX to the latest release as well. Everything came back up and was running fine, but during the night, I lost the registration on two of my sip lines (with the same provider) - the lines never came back up. After a bit of looking around, I noted that for that particular provider, when I have STUN active (default setting), the PBX sends out an INVITE with the public IP (the correct one).. and no response ever comes in. If however I disable STUN, the INVITE contains the private IP of the PBX, and everything works out just fine. The thing is.. STUN has been working for more than the last 3 years (using a variety of routers.. first with Linksys standard firmware, then various Tomato releases and more recently Teddy Bear's K26 builds on the RT-16N). I already downgraded the PBX software again (thank god I kept a backup of the config prior to upgrading as a downgrade wipes everything) - I guess I'll try downgrading the router firmware next but I was just wondering whether there was some change not mentioned in the release notes that could have something to do with it (at this point I'm looking at all the options - rollback, talk to the PBX makers and IPTSP).