TFTP error 4...after rooting many time usually works

[unclejemima]

I'm using a VPN connection with a Mitel 5000 PBX and a 5330 phone.  Network wise the VPN is working as it should...but plugging the mitel phone in gets DHCP, and then TFPT: main for 1 minute...then TFPT: err 4 and it restarts many time (like 20) and then will just work.

Any idea's?  What is this error and why does it eventually work without me changing anything?

[Tech Electronics]

unclejemima,

Does it do this with every 53xx series phone or just the one? If so I would try erasing the main firmware load and force it to download it again. I also would do this with the phone on site not remotely.

I think I ran into a similar issue with a 53xx series phone a few years back and if I manually set everything it would work just fine until it got the firmware download and then you could remove it and everything would remain fine after that.

Thanks,

TE

[acejavelin]

My experience is many VPN's just don't like TFTP... usually something about MTU size which many like to reduce to 576 or 900 bytes for some reason instead of the standard ~1500. This is one of the reasons we have gone to using Meraki almost exclusively since it has no issues with TFTP for site to site VPNs (I am sure there are others, but this was just what we selected years ago).

Usually the best bet is like Tech Electronics said is take the phone to the main location so that it can update it's firmware locally, then take the phone back to the remote site and when it boots up it will just check and see it's firmware is current and skip the TFTP process. A good solution until you upgrade the controller next time at least.

The other option if you have proper port forwarding at the 5000 location, is put the phone in TW mode and point it to the public IP, that can work better for TFTP.