While that may be based on OpenWrt, it is not an OpenWrt build, so it is not known what might be different and how. OpenWrt, being open source, is modified by OEMs and individuals in ways that often include different kernels, drivers, and application software. Those builds need to be supported by the author/distributor, unless they're "very close" to current OpenWrt.
As it seems as though you've got a proper driver available (assuming it shows up in lsmod), support for that build needs to go through its author/distributor.
Official OpenWrt builds can be obtained at http://downloads.openwrt.org Trying an official build may resolve your problems, or at least narrow down the possible causes. The group here can support those official builds.