Hi,
I'm experiencing issues with random connection drops and degradation, and wondering if anyone from Gocoax might be able to assist.
A network diagram is below - there are no other coaxial devices besides the modem and adapters.
Additionally, the XB8 modem has been placed into Bridge mode, so it should not be outputting any MoCA signals.

On the MA2500D hooked up to the router, I have "Preferred NC" ticked; on the others, it is off, the Link Rates chart from the adapter connected to the modem is below:

On the router's log, during some (but not all) of the instances of connection issues, the router notes that the host adapter loses its connection - "ether8 link down" followed by "ether8 link up (speed 1G, full duplex)"
In other cases, the adapter hooked up to the RT-AC86U will go down, with the Asus logs reading "eth1 Link DOWN", "eth1 Link UP 10mbps full duplex", "Link DOWN", and then finally "Link UP 1000 mbps full duplex."
There doesn't seem to be a rhyme or reason as to when or under what conditions things will go wonky. Is there any way I can try to pin this problem down?
For grins, I swapped out the MA2500D adapter connected to the router for the MA2500C in case it was a faulty unit. The MA2500C exhibits the same "ether8 link down" issue.
Sorry for late reply.
Looks like the MoCA adapters rebooted when the issue happened.
Could you check the firmware version of the MoCA adapter?