I'm experiencing an annoying issue where our Yealink T48U and MP56 phones keep rebooting, sometimes right in the middle of calls, and they all seem to reboot at the same time. This happens a couple of times a week. The phones that are rebooting are connected to switch ports with trunk configurations, allowing them to daisy chain between Voice and Data VLANs. The phones that aren't rebooting, the T33g models, are solely on a voice VLAN.
These phones are spread out across different switches and buildings, but we run a large flat network. When the reboots happen, our monitoring tools show an increase in bad packets, slightly exceeding the 0.01% threshold. This weird behavior started when our MP56s received a firmware update to AOSP, but the T48Us, which use SIP but are registered with Teams, are also affected. I'm suspicious there might be some sort of broadcast issue with the trunks since the Voice-Only Lobby phones, which are only connected to the Voice VLAN, aren't having any problems.
I've started using Wireshark on my laptop connected to the data network to investigate the broadcast traffic, but I'd love any advice on what else to check or look into, as troubleshooting this has been a real pain for the last few weeks!
3 Answers
When you brought up network broadcasts, it reminded me of a bizarre issue where USB-C docks flood networks with Ethernet pause frames when the connected device goes to sleep. Could something like this be affecting your phones?
You might want to check the switch logs to see if there's anything unusual. It's possible that the switch could be hitting its max load and resetting ports. Since all the phones reboot at the same time, it really could be a switch issue. Also, double-check if any maintenance policies from the Teams side could be forcing these reboots.
I'll look into that. It's just strange because the switches are in different offices and stacks. What are the chances they would all act up together?
The fact that all phones reboot simultaneously points to a switch issue. This could be due to configuration refreshes, power overloads, or something else entirely. Have you tried turning off LLDP on some of the affected phones? Just keep in mind that the bad packet counts are likely a symptom of the underlying problem, not the cause.
That sounds wild! We do have around 300 Dell USB-C/TB docks, so it's worth investigating. It’s similar to that weird iPhone issue with MRIs affecting phones. Crazy how technology can act up in unexpected ways!