Netgear R7800 (Main Router)-->Ethernet cable-->Netgear WNDR3700 (Dumb AP mode)
I followed the guide from the official docs here to set up my WNDR3700v1 in Dumb AP mode using Configuration via Web Interface LUCI
I also applied the setting for For devices with switch and dedicated WAN
Now when i connect the Ethernet cable to port 1 (not the wan) on my WNDR3700 i get a connection but it's not stable, if i ping my main router 192.168.1.1 i sometimes get an answer with 1ms response time but then it goes offline again and i have no internet connection.
I have tried all the Ethernet ports but the same thing happens.
Tested the Ethernet cable directly connected to my PC and everything works just as it should there.
So i dug up an old 10/100 switch i had laying around and connected the cable from the router, then from the switch to my WNDR3700v1 and everything works.
I followed you guide To a T.
Even re flashed it with the same version without saving the settings, power cycle and reset the settings again after successful flash just to be sure.
Still the same problem occurs.
3700v1 reports 100BaseT full-duplex on lan1-4 (tested them all) and then shortly after reports, no link.
Stationary PC Report 1000BaseT full-duplex, so i know the connection is solid from Router to PC.
When connecting to the switch 10/100 R7800 reports 100BaseT full-duplex. So that's correct. But the 3700v1 reports 1000baseT full-duplex, that's not right.
Shame i don't have a 10/100/1000 switch laying around to test with.
This reminds me of a similar problem i had many years ago with the Linksys WRT310N.
I think by that time it was a Opensource firmware bug the caused the lan ports to refuse to negotiate full speed. it was fixed with a firmware update later on.