Internet Connection Weirdness

By mark ·

I have a very complexing problem and I'm looking for any help or ideas
anyone may have.

We have 2 servers - one running SBS 2008 Standard and one running WS
2003 Enterprise which is also a terminal server.

We have Comcast business cable.

Since we set these servers up there has been an inconsistent but
frequent issue where the following happens:

1. External users cannot reach the RWW or associated services like the
Terminal Server.
2. Internal users cannot reach the Internet.
3. Internal users can work internally (email, database access, etc.)
just fine during these times.
4. The cable modem is pingable from the outside.
5. The cable modem is not pingable from the inside.

This happens somedays literally 30-40 times and some days 0 and some
days something in between.

This happens at all times of the day and night - including when there
are no users and when everyone is connected.

Troubleshooting we have tried:

1. Run the BPA and no issues.
2. Viewed event logs and no issues.
3. Checked server status (DNS, etc.) and no issues.
4. Comcast has been here repeatedly and have found nothing wrong on
their end but have said that it's a problem with our set up, our
switch, our software, etc.
5. Comcast switched the cable modem.
6. Comcast suggested unplugging the modem from inside the server
closet and plug it to another outlet. This seeemed to do the trick
for awhile and then back to the same behavior.
7. In order to see if it was our server/switch/etc. I plugged my
laptop directly to the cable modem one night. Nothing else was hooked
into the modem except the laptop and nothing to my laptop. Then I ran
a continous ping. It did have the same disconnect problem during the
night. My laptop was running Vista Ultimate.
8. Searched newsgroups, knowledge base, etc. etc. etc.

We are at our wits end. We have remote users who are repeatedly
interrupted. We have professionals who have to access our client
databases in emergency situations at night. Etc. So this is not

Any ideas at all?


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All Answers

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Equipment Closet

by Jacemg In reply to Internet Connection Weird ...

Hey Mark,

Try leaving the closet door open for some ventilation and have that laptop ping the modem again for awhile. To begin with I've had plenty of problems with cable modems from our ISP. My grandparent's modem had to be replaced multiple times.

This may seem like an obvious question, but is the cable modem power plugged into a UPS?
This not only rules out the problem of temporary power loss, but solved a problem with power spikes our commercial air conditioning unit was causing.

But if the modem is screwing up connected directly to the laptop, you have a case for a new modem, otherwise put your money where it's best spent and switch to another ISP.

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It gets weirder

by mark In reply to Equipment Closet

I really appreciate your reply. I spent 4 hours with the Comcast guy today and it all gets weirder.

1. Yesterday I unplugged the cable on my laptop and the Internet connection went down for everyone. Well today just for giggles I did it again several times. If I unplugged it and immediately plugged it back in the Internet stayed up. If I unplugged it for a few seconds (10 or so) then the Internet went down for everyone.

Since someone mentioned that I may have a bad laptop this is immediately what I thought about. Why though would it go down when I unlugged it? I currently am using Windows 7 RC for testing on that laptop. I haven't had a chance to switch back to Vista for testing.

2. After going up and down probably 20 times before he came, as soon as the Comcast guy came it didn't go down for about 2 hours. What was different during that time was:

*Me thinking it might be my laptop and Windows 7 RC I booted out of it and got to the login screen for Vista but I had not logged in. THe 2 are on different partitions.
*A couple users at this location left so their PCs were not being used
*A user at a remote location left so she wasn't using her PC

In 2 hours our Terminal Server hung up. I rebooted it and about that time the Internet went down. The reboot was longer than normal.

That didn't fix it all so I rebooted the SBS and after 2 hours of it trying to reboot I finally had to just hit the button.

After the TS was rebooted the technician hooked his laptop directly to the modem and our network was disconnected. He did a continuous ping and when he left 2 1/2 hours later it had still not gone down.

I'm not sure if he had stayed a little longer if it would have gone down or not just with his laptop.

The bottom line here is that I don't know what the bottom line is.

What Comcast is saying is that something on our network is shutting down the LAN side of the modem.

Seeing what my laptop did (or was it pure coincidence??) made me think they might be right.

Having it all go down when rebooting the TS and the 2 hour restart on SBS made me think they might be right.

I'm more lost than ever. Again there is no indication, event logs, etc. that there is a network/server/PC misconfiguration. Everything I know is in these posts.

Any further ideas?


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This should NOT fix the problem, but I've seen some weird

by Deadly Ernest In reply to Internet Connection Weird ...

behaviours in the past where checking and fixing these has resolved odd problems.

1. Check the IP address of the lap top, the modem, and your dhcp server.

2. Check network masks for all the above.

3. Check the dns addresses set in the system and all of the above.

4. Check if any of the above have static addresses and review if that is a problem.

5. Check the routing instructions in the modem router.

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