Okay, sded, I’ve run into the problem on two XP machines.
My desktop is a dual-boot unit running primarily WinXP Pro SP2 (Windows Vista Home Premium without CFP is installed on a seperate drive) and a wired connection to the LAN. My HP laptop is running WinXP Media Center SP2 with a wireless connection to the same D-Link WiFi router. Both machines are running Sophos AV.
There are several reports of loss of DHCP service for wireless with the new build. I have not been using DHCP, I use a wired fixed IP instead at home. Doesn’t seem to occur with wired. Switching to wireless DHCP for me only causes loss of the connection up status indication, not the connection itself. Others report success with switching their wireless to a fixed IP, but not all have evaluated it. Affects both Vista and XP. Are there any known changes to .204 that could impact this? Are there others having this problem? Not enough to complete a bug report yet, but more help/ideas/experiences would be appreciated. So far:
Workaround-use a fixed IP instead of DHCP=seems to work for some (all?)
Put an allow rule for UDP between computer port 68 and router port 67 in WOS
Make sure that the Windows Firewall service is on, even if not using it (from Google for Vista)-prob N/A
Make sure that discovery mapper and responder are on for the NIC
Make sure that SSDP discovery service is on
A few other things to try. 1) Make sure the DHCP client service is on. And the SSDP discovery service. 2) At your NIC, make sure that discovery mapper and responder are on, if applicable. 3) Try turning on the Windows Firewall Service (not the firewall) even if you are not using it. And please report back if fixed IP works for you, or at least changes the behavior. 
OK, where do I begin?
I am one of those “not so savvy” computer operators. But I DO KNOW that up until firing up my desktop this morning, I was able to have internet access. Not so after this morning. Have spent an ENTIRE DAY on the phone with Time Warner and D-Link, thinking it was one of these two to blame. Never THOUGHT it would be the firewall, until that “little something,” told me to DISABLE IT and try to connect to the internet. For some reason my IP address was changed to 192.?.?.? Once I received the correct IP address, and disabled the firewall, I’m great. I will be leaving commodo disabled permanently, or deleting it all together…what a PAIN!
I thought I was CRAZY! I don’t need this HEADACHE!
chuwl, there’s no need to drop Comodo. They’ve just updated the program today and it’s quite likely that they’d patched the problem. Don’t give up on the best firewall protection “for the money” just because of one hiccup. 88)
I have similar problems in XP Pro SP2 + D-Link wireless router. CFP is ver 3.0.18.309.
The router and its DHCP server are ok, because my work laptop works fine (without CFP).
Curious thing: connecting to wireless router’s Ethernet port by wire (i.e. not WLAN) works fine (using CFP) and after connection is made the wireless connection starts working too.
Static IP seems to work but it cannot be a long term solution.
I use static IP at home anyway, but haven’t had the problem. No word from the developers (or anyone else) on the nature of this bug, and no way to repeat it for them. Since it broke in .18, we can see if .19 fixes it again, but other than using static IP haven’t found a solution. Have you tried the suggestions above to see if there is any change? I haven’t found any reason for DHCP to be blocked, other than some internal change to .18 we don’t understand. 
(:SAD)
Well, after getting my desktop back up and running, my ability to network went adios this afternoon shortly after CFP 3.x was updated on my laptop.
Has anyone back-tracked the code that was changed in the software to figure out why so many folks have lost the ability to network wirelessly or connect to the Internet? ???
Things over here have deteriorated to the point that I’ve uninstalled Comodo firewall and have installed a basic version of ZoneAlarm (temporarily) so that I can have some degree of safety and a fuss-free and usable wireless network that actually works. Not good…
Last friday I got a message that a new version of Comodo Firewall was available so I installed the latest version on my desktop.
After rebooting I noticed that I was unable to connect to my network. I only got a 169.x.x.x instead of a 192.168.1.x address.
I started checking the cables and all settings, I even restored my Windows Xp Pro to a earlier state but I still got the same problem.
With my laptop (running Ubuntu) I was able to connect to the router so I was shure that the router was fine.
I uninstalled Comodo and then I was able to connect to my network again. Comodo was reinstalled and now everything is fine again.
Today I was working on the laptop of my father and got the same update message and I updated the firewall.
After the reboot I tested the connections, wifi was fine but the wired connection failed, again a 169.x.x.x address.
So I did the same thing as on my desktop, uninstall, reboot, reinstall, reboot. Under the first account everything was fine. When I tested a second account I was able to connect via the cable but I failed with the wireless connections. This was very strange because with the other account I worked fine 2 min before.
Did anybody have simular problems? I was so p*ssed this morning that I decided to remove Comodo from my father’s laptop and we are now using the Windows Xp firewall.
The desktop is running Win Xp Pro SP2 and the laptop Win Xp Home SP2 both accounts that I tested have Admin rights and the desktop and laptop are not connected to the same network.
Take a look at https://forums.comodo.com/help_for_v3/wireless_connection_problems_merged_topic-t19817.0.html for similar problems. Only solution found to work for most is using fixed IP address, as described there.
thx for the info
I noticed that both links speak about wireless issues after update, on my desktop I had the problem with a wired connection.
Haven’t seen other reports of that, but many wired connections already use fixed IPs or have already set DHCP profiles from normal usage. Added it to the list but didn’t change title. Have submitted a bug report to the developers to see if they can get more information on it with their tools. Try the fixed IP and see if it works for you.
Something else to try. Rain today, so tried doing a little logging with the neighbors wifi system and the new version, to see what the UDP traffic is. Still not DHCP, but maybe using something a little different. Set your NIC back to “get an IP address automatically” Then try adding the global rule:
Allow and Log/UDP/IN/Your router IP/any/any/any and see if you can get an IP. Usually should show traffic on port 1900, but there may also be broadcast messages
You may also need to add this to WOS.
Also make sure you do not have a global rule that blocks outbound UDP.
And you may also need to make a rule for svchost.exe
allow/udp/out/any/any/any/any
Trying to see if some of the (hidden) defaults changed for version 3.0.17.
Let us know if that helps.
Also, please tell us if you imported your settings from 3.0.16 or made new settings for 3.0.17 (or .18 if you went there directly).
When using fixed IP I was able to connect to the network but didn’t get any further then the router, so no internet connection.
Are you trying to make 2 connections from the same computer? What router are you using?
With my fathers laptop I was using a Linksys Wifi router. I tested the wifi and the cable connection seperatly. It worked fine for one account but the wifi failed on the other account.
OK, as long as the wired connection wasn’t up, the wireless should have worked. Your father isn’t using 3rd party firmware on a wrt54g, is he? Did you check that the router actually had a WAN IP? What kind of NIC are you using?
To be sure I understand:
You tried a fixed IP on a wireless connection and successfully connected to the router
The router had an internet address
There were no other connections to the internet from that machine
Your computer could not complete the wireless connection to the internet
You can try to open up UDP as suggested above and see if that helps. I am on Vista, using a wrt54g with tomato, and my connection works fine, but there are similar reports. I am trying to find out if something changed in the default settings between .16 and .17 that might be causing this problem for some users, but can’t replicate the problem myself.
There were no CFP network block messages
The router has a standard config, no 3rd party stuff.
The laptop is a Acer 4002 with build in Intel wifi adapter (Centrino platform)
The router had a wan connection, my brother was surfing the net on his desktop. The strange thing is that both nic’s (wired and wifi) where working fine on the first account, I logged out and logged in with a second account, under this account the wired worked but the wifi failed. The computer could see the wifi network but he didn’t get an IP.
I didn’t try the fixed address on the laptop. I tested a fixed IP on my desktop on Friday where I had the same issues after update, impossible to get an IP from the router.
nope
Something else to look at. I used Wireshark to capture all of the packets involved in the successful setup of a wireless internet connection on my computer. If any of you have the time, download Wireshark (or use it) to compare what is happening on your system. Note that the first two lines are really the DHCP connection to the router, the rest are involved in setting up the internet link afterward. Still looking for something not happening in these failed connections. 
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Okay, I recently installed Comodo and have noticed two issues that I believe are being caused by it.
The first is that every so often, I will lose my connection with my wireless network. I can quickly get connected again by repairing the connection, however, when doing so, it brings me to the second issue, it’s unable to clear the DNS cache.
I’ve seen several other people with the wireless network issue and one of the posts suggested I setup a static IP address. I did that and it had absolutely no affect on the situation. The connection will still drop. It’s a rather annoying problem that hopefully somebody can help me out with.
As for the DNS cache issue, I searched and saw several solutions that seemed extremely easy to do. However when I tried to go about that, I noticed that they were obviously written for a previous version of Comodo, as I have none of the tabs or options they want you to modify. Again, hopefully somebody can help me out with some updated solutions on this problem as well.