The reverse channel in serializer/deserializer pairs can be susceptible to low frequency noise especially when using Power Over Coax. The first thing to check should be the I2C bitrate speed and confirm the correct addresses are being used. I2C Communications can be confirmed using a logic analyzer to capture the full communications between devices and search for failure events. It is recommended that the default reverse channel be used when not using PoC as this is usually prevents most instability issues. High Immunity Mode (HIMM) is a necessity when using Power over Coax.
