Typically for me, if comodo firewall is the culprit preventing clients from accessing each other, I won’t even be able to see the other client in the network area of the (view computers and devices) tab unless I have first accepted the ip connection attempt alert on the client I am attempting to connect to. I wonder if somehow this alert was not answered in time or missed all together, preventing the communication.
Provided you have a global rule already established to allow incoming network trafic, one thing you can try is this…
On the client you are attempting to connect to, under advanced firewall settings, go to application rules, click the plus box in front of (system) to expand the rukes there. Check to make sure there is not a (block) rule there. If not, for testing purposes, double click (system), the appkication rule box should pop up, click the arrow at the bottom of the box, and click the (add) button. Next, create the following rule/ Action = Ask - Protocol = IP - Direction = In / Set Source Address, Destination Address, and IP Details to Any, click OK.
Now the rule should be shown in the established application rules box, make sure that this Ask rule is the topmost rule there, if not, you can move the rule up by clicking the tab at the bottom, when this is done, click OK again to close the box, and click OK again in the advanced settings interface to save the rule. You may want to restart both clients again.
What this rule will do is create an alert on that machine when ever another client attempts to connect to it, when this happens you can allow the connection request and click the remember my answer if you do not want to be bothered again with it. Of course you may want to go back into the settings and remove the Ask rule.
I acually prefer this setting as I am on a big shared network and like to know who’s attempting to peek at my machines. Not suggesting, but some devices and apps can get past this alert, so I created an additional rule to also Ask tcp and udp connection attemps In to also alert me.