We have many Yealink T19P-E1 phones with PCs, connected throught PC-port on a phone. A small numbers of phones have the next problem - PC(connected to the phone) after some time expiriences strong network bandwith's degradation. Restart of the PC doesn't help. Replacing of the phone doesn't help too. The only thing that helps is restarting of the phone by poweroff. We use VLANs (CDP and LLDP), but turning off CDP and LLDP on a switch's port doesn't help too.
Yealink support, unless they have a specific answer to this specific issue, would always ask what firmware and have you tried upgrading the firmware.
I find it odd though, that replacing the phone (with a phone that doesn't have the issue I assume?) doesn't help but restarting the existing phone does.
Are you using DHCP for the phones or Static IP?
Perhaps even a more basic question needs to be asked here:
What is your cabling infrastructure, and are you 100% sure that it is installed and operating as per industry standards?
99% of the time we find customers that simply drop VoIP installations onto existing offices/buildings without even bothering to check and make sure the network wiring was done properly in the first place. A PC can drop packets and toggle link speeds without anyone noticing, but when you put a phone on it that's a whole different ball game. Since you have already stated that replacing the phones does not make a difference, I would suggest having a proper cabling company come in to check the wiring (or at least moving one of the "suspect phones" directly to the switch in the LAN room, and seeing if the problem goes away when it's there.
You would not believe how many people in the world think that the color code and termination standards for Cat.5e/Cat.6 are just "Arbitrary recommendations" or do not know about them at all lol End of the day though get a proper cable test done and I bet you will find the source of the problems there (either wrong wiring, loose pin/punch down, crosstalk or some other physical fault).
The phones are probably negotiating to 100M, but then over time as packets drop and strange things happen on the link, they end up falling back to 10M or even half duplex.
We've made some experiments and found following:
Cable system is OK.
Issue occured only if the phone has huge Voice VLAN 255.255.248.0 with ~ 1200 MACs(PC's VLAN's size doesn't matter) and PC has Dell's MAC 14:b3:1f...
If we change MAC on PC to the other, the problem doesn't occured.
(04-11-2019 08:14 AM)Sur Wrote: [ -> ]We've made some experiments and found following:
Cable system is OK.
Issue occured only if the phone has huge Voice VLAN 255.255.248.0 with ~ 1200 MACs(PC's VLAN's size doesn't matter) and PC has Dell's MAC 14:b3:1f...
If we change MAC on PC to the other, the problem doesn't occured.
I tried to test and know that it is the same problem.
goldenslot