Model : TL-WA801ND

Hardware Version :

Firmware Version : 160022


I have a problem with the muli-ssid vlan functionality of the TL-WA801ND AP's, but only the v3 version.
I have 4 x TL-WA801ND's, 2 on v2 hardware and 2 on v3 hardware.
The v2 versions are configured with 2 vlans and work perfectly.
However the 2 x v3 versions (configured identically to the v2 versions) connect and get a dhcp address but the connection just dies after a few seconds and never completes loading a web page, for example.
Looking at the status/statistics figures it seems to recieve ok but the send packets are about a tenth of the recieve.
I am using the eu 3.16.9 (160022).bin firmware and have reset/reloaded so many times, I've lost count.
Any ideas ?