XG-1537 transparent bridge traffic

[bmf7777]

i'm using an xg-1537 as an IDS/IPS appliance with WAN port as the management port connected to another router ... igb3(eth1 out from other router)-ibg2(eth1 from other router) form a transparent bridge which loops through local lan for IDS/IPS monitoring ... these interfaces are working fine. however, i see igb3 traffic pattern on the wan(management port) which has a firewall rule allowing only 443 access for gui access ... any ideas why this traffic is showing up on my XG wan(management) port and how to block or prevent it ? thanks in advance