We are now seeing intermittent connectivity issues on computers connected to the PC port on our 7841 and 8841/8851 phones after a CUCM upgrade to version 14.0.1.13900-155. The phone firmware on the 88 series phones is sip88xx.14-2-1-0001-14 and sip78xx.14-2-1-0001-14 on the 78 series phones. The computer works fine when connected directly to the wall port but when the phone is added, the problem starts. Everything works fine for a few minutes but then the computer indicates it no longer has internet. If you wait long enough, connectivity returns but only for a few more minutes. If I release/renew the lease on the computer, connectivity returns. When looking at Wireshark trace, the computer is sending arp requests but never gets a reply. We have confirmed the core router is providing a reply, it just doesn't make it through the phone to the PC. The computer can't even ping the gateway when this happens. We have about 1200 phones deployed and are currently seeing this in a handful of locations. Is there anything in the phone's switch that would block this traffic? Is there a log I can see in the phone that would help troubleshoot? I looked at the console logs but that doesn't show anything helpful. I pulled a PRT report, but don't know which log to look at, if any would even be helpful. This problem didn't happen when we were on CUCM version 12 and nothing has changed in the computer configuration. I have not tried turning on the span to PC port and doing another trace but I've considered that.
