Forums Connection Issues Very strange disconnection problem

I'm having a very strange problem with disconnects which I've not seen before, though I've been using mIRC for 10+ years.

1. The problem is remaining connected to Undernet.

2. Everything was fine until last night. I had no problem staying connected, unless Undernet itself was having trouble, in which case plenty of others on my channels were having similar problems at the same time. This is not the case right now, nobody else is having a problem remaining connected, only me.

3. Last night, my cablemodem went out, and I had no internet connection for 30 minutes. Later I checked and found out there was a Comcast outage in my area, but it was fixed in 30 minutes.

4. However, when my internet connection came back, I started having a problem with frequent disconnects from Undernet.

5. Basically, when I connect, I am immediately lagged. I see 4-5 lines of scroll appear simultaneously, with long periods of no scroll in between. In about 4-10 minutes, I am disconnected, and my client automatically reconnects again. This has been happening continuously since last night, for over 18 hours now.

6. I am NOT disconnected from other networks. On the same mIRC client, I also have windows open to Freenode and Dalnet. There are absolutely ZERO disconnects there. Only from Undernet.

7. I thought it might be a lag/packet loss issue, so I opened a Command Window in my Windows 7. I am doing a continuous ping to google.com for the past 30 minutes and watching the ping reply and TTL. Nothing changes during any of the disconnects. There is no increase in ping time, no packet loss whatsoever.

8. And now for the odd thing. Just to check, I opened another IRC session using another client (XChat). I used it to connect to the Undernet, join the same channels as I'm on with mIRC. I'm connected to the Undernet using the same server on both clients (Chicago.IL.US.Undernet.Org). But I get NO DISCONNECTS on XChat, only on mIRC.



So why is it that mIRC keeps getting disconnected from Internet every 4-5 minutes, while XChat does not, even when they're both running on the same computer with the same wired connection to the same cablemodem, and connecting to the Undernet via the same Undernet server?

Any help is much appreciated.

This is reported occasionally and appears to be due to an ISP checking for IRC connections and disconnecting them. mIRC is the most widely used IRC client, so ISPs often check for connections that look like they are from mIRC. You can find a discussion on the same topic here.