Random, intermittent internet disconnect
Posted on 2011-05-12
For about the last month, we have had intermittent internet connection issues. In a ping test we have 0% loss then suddenly 100% loss for 1-3 minutes (50-60 time outs), then 0% loss again.
The network is in a K-12 Private School.
The network configuration is:
Internet Cable >> Cable Modem >> Sonic Wall NSA-240 >> 24 port switch >> the rest of the network about 85 computers. 1 windows 2008 server runs the network.
Time Warner has been here twice and replaced the cable modem twice.
Sonic wall tech support has crawled all over the settings and logs for the NSA240 3 times to make sure it is configured correctly, plus it was new in February.
I have had at least 3 different switches in place.
I had removed the sonic wall replacing it with a router and after a few days the problem returned in the early stages of this issue.
And we have found some things wrong such as a bad cable modem, switch, cable and one computer, but the problem still persists.
The outage may occur many times a day or go 3 or 4 days with nothing.
It seems to go out more often at the beginning of a period or right at the end of the day where a load is placed on the network.
The internal network continues to function fine. There is no loss internally and those connected to the server work fine. ONLY THE INTERNET CONNECTION IS DOWN. So I have no reason to believe a specific computer is poisoning the network.
During an outage, I cannot ping the sonic wall nor the internet. I thought resetting the devices helped, but I am not so sure because it usually comes back on its own.
Disconnecting the network a cable at a time from the switch to see if the removal of part of the network corrects the problem quicker did not show anything. I disconnected all but the laptop doing the ping test and the outage still continued.
Time Warner did upgrade it's equipment in our area to accommodate higher data speeds and our problem started during that period, but time Warner has repeated claimed it is not them after checking their system and I do think the trigger is internal, not external.
We do have a mixed network in that Teachers often use their own laptops, plus there are 2 private residences (On site parsonages) and a church network on the system.
Unless there is a breakthrough soon, one of my next steps is to prohibit none school computers from the network and see if it isn't a private computer messing things up.
I have looked through the server logs and while there are some error messages, nothing coincides with the outages.
I have consulted with two other IT guys and they had no suggestions on what to try next.
So the question is:
What have I missed and what haven't I tried? I am looking at the antivirus to make sure the Avast is keeping everything updated. I do see some issues there and it may become a different post.
I'm attaching a bunch of points to this question because I don't think it is going to be easy to resolve.