Comodo Firewall is blocking access to a second computer

Comodo Firewall is blocking access to a computer in my local network. From time to time this strange behaviour appears. Two computers are connected to a router. There seems to be a problem with IP, because this blocking disappears immediately after DHCP assigns different IP to a blocked computer. I use dynamic DHCP (Start: End: I’ve already tried to use static DHCP and it solved my problem, but my router is not able to assign new IP to a computer which is woken up from sleep for some reason. (I had to reset that router to get a new IP). I found out that blocking disappears when I disable Comodo Firewall. I tried to add a range od IPs to network zones, but nothing changed.

(COMODO Firewall 5.3.175888.1227, Defense+ permanently disabled)

Hello; If you add them to the network zones thru IP Rang to then Define them as a trusted network
CIS > Firewall > Stealth Port Wizards > Select them

Does this work?


It’s strange, but it doesn’t. That was the first thing I did on both computers. I’m using Comodo - Firewall Security configuration. When my network is blocked and I switch to another configuration profile, then all works fine. I’m just not able to find out what’s the difference between these two configurations.

have you tried disabling fragment IP option
CIS > Firewall > Firewall settings > advanced > uncheck 'fragmented ip"


Not yet, but I’ll give it a try when this behaviour occurs again. Thanks for your advice.

Hi guys, it happened again today and I finally found out what the problem was. As I mentioned before, I have local area network with ip range - And this area was defined as a trusted network. I’ve tried to disable blocking of fragmented IP datagrams, but no change. Then I’ve tried to remove 3 host names from Blocked Network Zones and now it works! Isn’t it a bug? I mean, 3 blocked host names but none of them was my laptop nor desktop pc, so why was my laptop isolated from network?

what were the host names?

Blocked host names:

edit: my laptop’s host name is S****-NOTEBOOK (without * of course). I wonder if firewall remembers IPs of blocked host names. If yes, then maybe that’s why was my laptop blocked. I use dynamic dhcp, so it’s possible my laptop has sometimes IP which was used by blocked computer in my network before. And I think it blocks IP instead of host name.