Troubleshooting Tip: How to resolve video not loading on CCTV due to firewall policy

Example:

When CCTV is directly connected to an ISP router, the video loads properly on CCTV. However, the video cannot load properly when connected to FortiGate, even when the security profile is disabled on the firewall policy.

To troubleshoot: This could be due to tcp-mss sender and receiver settings on the firewall policy.

To resolve this, change the mss to a smaller value such as 1388 or below until the video loads. In addition, ensure that no security profile is selected in the firewall policy which involves the CCTV.

config firewall policy  (CCTV)

    edit 1

        set tcp-mss-sender 1388  
        set tcp-mss-receiver 1388

    next
end

Verification: A CCTV loading sign does not appear on the video after setting the smaller tcp-mss values in the firewall policy which involves the CCTV.

Related article:

Technical Tip: Setting TCP MSS value