I have a question about this topic —> https://forums.comodo.com/help-for-v3/fritzbox-port-14013-resolved-t18187.0.html;msg125440#msg125440
I think it is not resolved, because deactivating an important feature is not the way to solve a problem. I am still looking for a solution in our firewall rulesetting. Has anyone an idea? This could be a reason to use another firewall, so I think it is very important!
Easiest route here is to make the IP address of your Fritzbox a trusted network. In the following I assume you know the IP address of your Fritzbox.
First step is to define a network zone for the Fritzbox alone. Go to Network Zones and make a zone called Fritzbox with a single IP address (the IP address of the Fritzbox).
When done go to Firewall → Stealth Ports Wizard and choose the first option Define a New Trusted Network and Make my Ports Stealth for Everyone Else and fill in Fritzbox as the network to be trusted. When done click OK.
Now check Global Rules and the rule for system in Application Rules and see that they are adapted.