|PHY violates IEEE specification for jitter||
The TS-4900 PHY's published errata here includes items added on 07-26-16 for "1000BASE-T Transmitter Jitter fails to meet IEEE compliance specification" and "1000BASE-T Transmitter Distortion fails to meet IEEE compliance specification". Both errata can cause linking issues, and the Jitter related errata can cause packet loss with some link partners at 1000Base-T.
|Change out the link partner on the other end of the network cable. If the PHY in the linked device meets or exceeds the IEEE specs it will compensate for the errata of the PHY on the TS-4900. Alternatively reducing the ethernet speed to 100BASE-T should resolve the issue.|