This is strange. I have a firewall filter rule (FORWARD chain) on a Mikrotik router that drops invalid packets. For some reason, it's dropping packets that are to/from the same interface, my LAN subnet. Lots of packets are hitting the rule and being dropped. Here's an example of what I see when I log the drop rule:
forward: in:bridge1 out:bridge1, src-mac 70:88:c2:da:51:61, proto TCP (ACK), 192.168.90.51:50138->192.168.90.11:49677, len 40
Why would that traffic even hit the forward chain if it's to/from the same interface/subnet?