I have a Hex POE (RB960PGS) configured as a Bridge on all five ports plus the SFP port. FW 6.48.6. Hardware offloading is enabled on all ports. The SFP port is locked to 1Gbps. All other ports have auto-negotiation enabled. Ethernet Ports have port isolation enabled to all other ethernet ports, so Ethernet ports do not forward traffic to each other. They only forward to the SFP. No other configurations. I have many other routers of the same model at many other locations performing well with the same config.
One of the ethernet ports is misbehaving, currently auto-negotiates to 10Mbps, and often loses link. Normally it auto-negotiates at 1 Gbps. This is an installation at a tower in a remote location, co-located with FM radio transmitters. I suspect that the cable is suffering from RF interference. I will travel there to check in a couple of days. Until then I am trying to write a prioritized list of tasks and equipment so that I can use my time efficiently when I go there.
PROBLEM: The strange behavior is that when the bad 10Mbps link starts to get saturated (at about 8.5 Mbps) the other ports on the bridge start to slow down to about 10Mbps, and the latency to/from the devices connected to these ports goes from about 15ms to approximately 250ms. Their negotiation speed does not change, but they begin to behave as if they were on 10Mbps, but in an unstable way. CPU and memory usage does not increase. If I disable the faulty port, the other ports speed up again and the latency goes back down to 15ms. Also, sometimes if I disable the faulty port, the others stop trafficking for 10-20 seconds while they re-negotiate their link speeds. Yet other times, when I disable the faulty port the watchdog forces a reboot, indicating an irrecoverable crash or hardware issue.
Is this normal behavior? Does a faulty link on one port affect all of the others on the same bridge? Or am I observing a hardware issue and should replace the unit?