You would need to check the Phone's Log Files as described => here <= and in addition set the Logging Level for the Support Object to Event 3 or via a configuration file to log.level.change.so="3".
If the PC Port is unplugged and replugged a Message like this will appear in the Log:
0215094822|so |3|00|Link status is Net up Speed 100 half Duplex, PC down.
0215094824|so |3|00|Link status is Net up Speed 100 half Duplex, PC up Speed 100 full Duplex.
The Phones can support dot1x / eapollogoff but you would need to contact your Polycom Reseller for further support on this.
Polycom Global Services
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