Yealink handsets not registering after being powered down

hi all - I have a batch of 12 yealink phones that have been working well with asterisk / freepbx for almost two years, yesterday we had an office move around and 6 of the phone were unplugged for a couple of hours, when powering them back up they would not register, no changes in LAN/switch/router - the ones that weren’t powered down are still working as they should be - any thoughts on where I should start looking?

any help would be much appreiated as I am a novice with freepbx / asterisk

thanks :slight_smile:

My guess is that a “harmful” change was made some time ago to iptables, switch configuration, hardware firewall, etc., but there was no immediate trouble, because of an existing ARP or NAT association, cached DNS record, connection in Established state, etc.

Do your failing phones show the correct time? If not, your connectivity issue is unrelated to the PBX (unless that’s also your NTP server).

Next, run tcpdump on the PBX. Are REGISTER requests coming in from the failing phones? What responses, if any, are going back out? If this doesn’t help find the trouble, please post some details about your network – your OP didn’t even say whether the PBX is on your LAN or in the cloud.

Another thought: If you are using Endpoint Manager or other auto-provision scheme, an error may have been made in the configuration, but the phones didn’t pull the new (bad) files until they rebooted. To check, use one phone’s web interface to see if any network or account settings are preventing it from registering.

Thanks for the replies everyone, the asterisk server is in a datacentre and my offices all have a site-to-site VPN as a link to the asterisk server.

After using wireshark on the LAN side and seeing sip register requests going out, then using tcpdump on the asterisk side seeing that they were never received - it was a firewall rule put in place (after the handsets were configured) to block all sip traffic except those originating from the source IP of our sip provider, an extra rule had to be put place to allow sip traffic from the internal subnet i was in - this allowed the handsets to register again.

I am still learning from all of this.