I have 3 x RB951Ui-2HnD router board (RB) running 6.31 with a wlan1 bridge with ethernet 2.

STP is disabled on the Mikroti bridge (protocol mode set to None).

I have a HP ProCurve 2520-24-PoE switch (flat, no config) connecting to the RB951's (I have tried with the ProCurve having Spanning Tree both enabled and disabled, plus with Mikrotik bridge set to RSTP and also None, makes no difference).

Using a number of DELL Windows 8.1 clients i connect to the access point and Windows spins connecting saying it is taking longer than usual. Clients connecting via Ethernet cable get an IP address instantly.

If i set my WiFi NIC on the Windows machine to a correct IP statically I am not able to ping the server, or the router, until about 90 to 120 seconds after connecting... so seems my packets are being blocked.

If i log in to the RB on winbox from the laptop whilst i am unable to connect, from the terminal on RB i am able to ping the server and gateway.

Any ideas what on earth is going on? Is there a compatibility problem or some kind of spanning tree in effect?