I am having difficulties with a BE800 which will download up to 950mb/sec on a 1gb/sec symmetric broadband link without problems, but typically seems to support only 1mb/sec – 250mb/sec of upload speed.    Without the BE800 in the path, upload speeds are 500mb/sec – 850mb/sec.

I have tried in both wired and WiFi AP modes; I have tried over WiFi and wired; I have tried with Macs and PCs and iPads and iPhones; I have tried multiple Cat7 and Cat8 cables; I have tried with and without intervening layer-2 switches between the BE800 and the ISP router/modem (it's GPON and proprietary, so I have to use their router/modem to connect to the ISP); I have tried with the copper and the SFP 'WAN' combo 10GigE port on the BE800; I have tried with the standalone 10GigE copper 'WAN' port on the BE800; I have tried with auto-negotiate on the BE800 wired ports; I have tried specifying the rate and duplex on the BE800 wired ports; I have tried with flow-control enabled on the BE800; I have tried with flow-control disabled on the BE800; I have tried with IPv4 only; I have tried with IPv6 only; I have tried with both IPv4 and IPv6; I have tried with QoS enabled; I have tried with QoS disabled (at least in the UI).

I even tried some beta firmware posted here not long ago.

None of it matters. 

This is not a WiFi issue, because it happens whether the devices in question are wireless or wired.  It is not a routing issue, because the topology is simple and the problem occurs whether the BE800 is in layer-3 router mode or AP mode.

The hardware is version 1.0.  

If I replace the BE800 with a similar unit from another manufacturer, all these issues go away.   The problem is specific to the BE800, which I just bought last week.

Any relevant guidance and/or similar experience greatly appreciated, many thanks!

[I also find it highly irritating that a managed mesh is only supported in layer-3 routed mode, but that's a different discussion.]