ZenWiFi BT10 — Extreme download/upload asymmetry on mesh node via MoCA backhaul

[CraigBee]

BT10 mesh (2 nodes). Google Fiber 3 Gig. MoCA 2.5 backhaul (GoCoax, 2.5 Gbps) between house and barn.
Problem: Barn mesh node: download capped ~270 Mbps, upload hits ~1.5-1.7 Gbps. Main node in house tests fine. Ran at full speed for over a year — issue started ~1-2 months ago.
What I've tried:

Firmware downgrade to October 2025.
Full factory reset on both nodes (no config restore)
Replaced the GoCoax MoCA adapters at both ends

Upload speed on the barn node proves the MoCA link and WAN are fine. Something is throttling download specifically through the mesh node.
No QoS, no AiProtection, no traffic analyzer enabled, no MLO. Everything at default.
Anyone seen directional throughput issues on BT10 AiMesh nodes? Feels like a backhaul-to-LAN forwarding issue in the download direction only.

 

[degrub]

Just some ideas -
Any chance of the house 2.4 GHz reaching the barn at above -75dB RSSI ? Turn off the barn node to check.

Any difference if you remove the barn unit as a node and add back as an AP instead ?

What do the moca modem diagnostics indicate on the modem to modem link bit rate chart ?
Power output from each modem ?

 

[jzchen]

What speed test results do you get if you connect a laptop at the barn MoCA instead of the BT10...

 

[tgl]

A lot of people have seen weird throughput asymmetries with 2.5G MoCA adapters. My own adventures with that are chronicled in this thread, along with some other peoples'. AFAICT it comes down to these MoCA devices being really sensitive to the buffering behavior of the immediately-connected devices, and it's hard to tell which device is more to blame. (I would tend to blame the MoCA devices first, but then again I have heard some similar stories about other gear.) About all you can do is try to find switches that play nice with the MoCA adapters and then make sure there's one of those on each end of the MoCA link.