invalid packets with repeater

Hello,
we are using router OS v 3.30
I need to connect 2 dlink wireless devices to router (dap-1360), 1 as access point, 2nd as repeater.
it works absolutely fine when only AP is connected. when I connect also repeater, I cant access internet with the laptop.
I found following entries in firewall log

Oct 28 16:41:13 192.168.50.1 firewall,info FWD:INVALID forward: in:ether1 out:ether2, src-mac 00:1c:26:66:05:78, proto TCP (ACK,FIN), 192.168.51.31:64377->90.156.178.18:80, len 20

I cant ping router, or anything outside LAN. I disabled rule that blocks INVALID traffic, but it doesn’t change anything.

I m 99% sure its MT problem, because I tried same setup with 2 other routers, and internet was working.

thanks,
Igor.