AC68U Bridge, Bad internet speed and drops. Error every third second: kernel: br0: received packet on eth2 with own address as source address

Hi.

Im new here, have read post here in years but never needed to post anything.

I have a AC87U as main router using stock firmware 3.0.0.4.382_51939 every thing is good here.
I have a Netgear EX7000 as bridge using the 2.4GHz band, works fine.
When i set up my AC68U with Merlin 384.19 as Media Bridge using the 5.0GHz band i get bad internet speed...

AC68U Bridge, Bad internet speed and drops. Error every third second: kernel: br0: received packet on eth2 with own address as source address