Hello!

I have a 2760 on a PlusNet FTTC service, which in itself is working well. Firmware 3.7.5.4. Sync speed 20/80Mbps. Wired throughput and stability are perfect.

HOWEVER, the WiFi network which is delivered by 2x NetGear WN604 APs has unexplained packet loss after a few minutes of connectivity. For example ping 8.8.8.8 just stops working whilst wired clients have no connectivity interruption. The AP's are cabled directly to the 2760. After some more time it appears that the NetGear crashes completely such that the attached WiFi clients cannot even ping its own management interface. The APs are about 6 months old and have been working fine until the router was upgraded from NetGear N150 (for ADSL) to the Draytek (for VDSL).

I mirrored a 2760 LAN port and ran tracert and can clearly see the inbound ping responses being sent to the AP with correct source & destination MAC, and nothing apparently wrong with the frames, however they never appear on the WiFi network. Odder still is that responses on 1st and 2nd hop are received, but subsequent replies are not. And there is no browser connectivity. This is consistent across WiFi end-points, meanwhile wired clients have uninterrupted, stable connection. I cannot see any difference in the frames (captured using tcpdump on Ubuntu via wired connection) between those that are delivered and those that get lost in the AP.

I reduced the network to one AP - no change - then changed the AP to a NetGear N150 (unfortunately I don't have any other brand to hand) with exactly the same result. Next I changed the AP for a Linux box running hostapd (bridged) and the problem is resolved, but the signal is very weak from the Qualcomm Atheros AR9285 so not really a long term solution.

Hence I'm pretty much stumped. There seems to be something about the Ethernet traffic generated by the 2760 that is causing the NetGear devices to either drop the traffic or degenerate into some kind of crash state.

I'm happy to change the NetGear APs - thinking of Draytek AP700 (for price) or 900 (for dual-band) but would prefer something supporting quick migration (802.11k/r) like the Ciscos - but obviously don't want to fork out a few hundred pounds for stuff that could have the same issue!

Any thoughts or advice greatly appreciated.

One thing to add - I cabled the AP's via a separate GbE switch, but the result was the same.

VDSL -> 2760 -> WN604 => packet loss
VSDL -> 2760 -> Switch -> WN604 => packet loss
VSDL -> 2760 -> Switch -> Ubuntu PC w/hostapd => no packet loss

but

ADSL -> N150 -> WN604 => no packet loss
ASDL -> N150 -> Switch -> WN604 => no packet loss

Also, IPv6 is disabled on the Vigor 2760.

maybe silly idea but try at Lan > general setup > tick the small button "Force router to use "DNS server IP address" settings specified" perhaps Lan 1 ... then details page add the dns servers manually
Also check the dhcp at the netgear?

EDIT
ooh i see is via switch sorry

Thanks, it's definitely a layer-2 issue though. I just hooked up a 'Technicolor TG582n' as a AP, and it works fine. So it seems there is a compatibility issue between the Draytek 2760 and NetGear's access point implementation, at least in so far as that implemented in the N150 router and WN604 AP.

I should probably have added that DNS/DHCP are being handled by a Linux host and a Raspberry Pi. There is no IPv6 in the network.

For the benefit of the search, I ultimately replaced the technicolor with a pair of TP Link WR710n devices functioning as access points, and stability and coverage issues have been completely resolved. These devices can also be run on OpenWRT which is also stable so far (on 14.04 trunk).