[Solved] Netgear R7800 performance (bad port in external switch)

I've recently installed a netgear R7800 running OpenWrt 18.06.1 r7258-5eb055306f

Sketch of network configuration:

Linux box acting as NATting router to rest of world. Internal wired "backbone" is on subnet The R7800 is configured as a plain router (no NAT) with its WAN interface on, and its LAN side serving Upstream link is FIOS rated at 75/75Mbps.

Doing some testing reveals that my download performance is good, I can consistently hit 80Mb (better than what VZ says they've provisioned me at). But for upload I get only about 10-11 Mb. Same for either WIFI or plugged into a port on the back of the R7800. If I plug a laptop directly into the side, I can consistenly hit 80Mb both up and down.

It seems like the R7800 isn't doing a good job on upstream traffic. Is this what I should expect? Anybody got hints or pointers to ways to improve my upstream performance?

TIA for any pointers.

Have you tried testing performance using a "regular" computer (like a laptop) plugged in directly to the R7800?

Also, if you are using, it would appear that you have made some modifications to the configs of the R7800. My first suggestion would be to take the R7800 that has been freshly flashed with OpenWrt, plug in a laptop, and run your performance tests. That would at least eliminate the possibility that some config you made was the cause.

If the performance is still unexpectedly low even with a vanilla, out-of-the-box OpenWrt, then my next recommendation would be to start swapping out Ethernet cables, in the off-chance that one of the cables has started going bad.

And if that still doesn't change anything, then it's possible that one or more of the ports on the R7800 might have gone bad. One way you could test that possibility would be to plug one computer into one of the LAN ports, and another computer into the WAN port, and try to do some large file transfers between the two computers. You might need to do some configuring to get one of the computers to communicate with the WAN port, since by default OpenWrt has the WAN port set to behave as a DHCP client, and the vast majority of computers also behave as DHCP clients.

Testing regular computer: yes. My work laptop, or one of my desktop systems, when plugged into my wired network (upstream of the R7800) gets 75-80 Mbps up and down. I plug that same laptop into a port on the R7800, or run it wireless through the R7800, and my download speeds are about the same, but upload gets way slower.

The only config I modified on the R7800 is to turn off NATting, and tell it that its LAN side is serving My wired network DHCP server hands it for its WAN port. I've also opened up two ports on the WAN side, to make it easier to admin.

I tried turning NAT back on, but that didn't make any difference. I've tried a couple of cables, same symptoms.

I don't know anything about the hardware configuration; does the WIFI data path go through the same places as the wired LAN ports? It seems unlikely to me that a single bad port would cause all the LAN side, both wired and wireless, to degrade in one direction, but I may not be thinking about it the right way.

Thanks for the ideas . . .

I'm thinking maybe marginal cable on the WAN side, with receive ok but transmit going wonky.

Hah! Thank you for jogging me in the right direction!

The cable was fine, tried a few more with the same result. But it got me thinking about other similar stuff to try. Turns out the switch into which the R7800 was plugged has one port which is degraded. I tried a different switch on my backbone, and got dramatically better results.

I'm now convinced I need to examine the rest of my network, any place where I care about performance. The R7800 appears to be fine.

Thanks again!

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