OpenWrt support for Linksys MX4200

Cross posting -- are there any known issues configuring VLANs on the MX4300? I'm getting very bad performance using vanilla openwrt (snapshot) on an AP connected over a trunk port. Connections to SSIDs assigned to the VLAN time out when using the NSS build, so I can't try that (I thought h/w acceleration might help). I've been searching to see if anyone else is having these kinds of problems but haven't found anything. Thanks

Details of my setup: