How can I understand which rule is blocking?

How can I understand which rule is blocking it?

I have an allow rule for the application, but I still see the block!
What is “Windows Operatin Sysytem” application???
The list of rules is no such.

You have a block rule under global rules. If you want to have an application to receive inbound connections you need to create an allow In global rule in addition to the application rule.

I have to make two identical rules ??
But why?
I’m already allow incoming!

Because global rules are checked first for incoming connections then application rules, for outbound connections application rules are checked then global rules. Here is the help documentation explaining the process.Global Rules, Firewall Protection, Best Firewall, Network Connection - COMODO

Edit: comodo will also block fragmented IP packets regardless of global or application rules if you have ‘Block fragmented IP traffic’ enabled in firewall advanced settings. You can tell if CIS is blocking fragmented IP packets if the source and destination ports for TCP or UDP are 0 (zero).

global rules are checked first for incoming connections then application rules
understood. thank

I remember something!
i have internet - router - comodo FW - utorrent
No global rules for utorrents port, but it can accept incoming connections.
why my second app can not operate in the same way?
why it can not work as well as utorrent - without global rules?

What does your global rules look like? can you post a screenshot showing all global rules. I believe utorrent uses UPnP to dynamically open ports.

utorrent uses UPnP
your global rules
all default -- UPnP work with comodo FW? how can I disable this for all apps in CIS?