Been running a Beryl for a couple of years with no issues on out the box firmware and always got a 5 gig WIFI link speed of 866 up/down with it 2 rooms away - after update to latest firmware I now get a drastic reduction in link speed which seems tied to reduced range as the link speed return to 866 if distance to router halved by moving it closer.
Some users say that wireless performance of the 3.x version is better than 4.x, and say that there is a difference in the Openwrt kernel.
But we cannot reproduce this issue.
Have you tried including the v3.x version?
Which box firmware version are you referring to?
As new the unit was on a v3 varient, I updatewd to v4 latest and WIFI performance degraded, tried to rool back to v3 but performance of WIFI still poor.