I was pretty excited to try out the firmware. LACP suddenly stopped wroking - even though it was configured as originally working on stock firmware. I tried setting it in LACP and static modes.. neither worked (configured switch to match).
Symptom is it seems to be retraining every few seconds.. you can ping the R9000 via LAN 2 pings, followed by 4 drops, followed by 2 pings, followed by 4 drops..
I tried DD-WRT - OMG - I couldn't even get LACP going as interfaces didn't seem to match hardware (eth0-2 vs. 6 total eth ports? Nothing to bond!)
~Matthew
I discovered the same problem for LACP. Latest stock firmware works fine.