IP Problems - Internet access only affected

[EasyUp Web Hosting]

Hey Guys,

I have a very strange problem.

First, the setup. 1x SBS 2003 server and 1x Server 2003 Std (backup server). 2x 10/100 3com unmanaged switches. ADSL internet access. +- 15 users. Untangle firewall.

The problem is random, as in not always the same user or same ip or time of occurrence.

I use DHCP to assign IPs to the pcs, but a couple of days ago, one or 2 pcs will loose internet connection. Everything else works fine, except for internet access. If I change the IP from DHCP to static, same ip, same problem, change it to a different IP, then it works again. If I use the original IP on another pc, that pc won't have internet access.

I have tried to reset the IP stacks, DNS flush. Restarted the untangle box. Don't know what else to do. Also, if I change the pc from DHCP to a different static IP, it will work for about 2hours and then it stops again, then I can change it back to DHCP and it will work again, for about 2 hours.

Any thoughts on what else I can try.

 

[ITCynic]

You indicate a total of 3 machines/servers/firewalls + 1 router

How many are providing DHCP ?

Just for interest sake, what are your specs for the Untangle box ?

 

[EasyUp Web Hosting]

SBS server is handling the DHCP requests.

Specs of Untangle:
Intel E7400
4gig DDR3 ram
250gig HDD
3x nics (only 2 used ATM)
onboard vga
Untangle 7.2something (the latest one)

 

[ITCynic]

Does a scan with the SBS 2003 BPA show anything? http://www.microsoft.com/downloads/...7A-DE19-49BB-800F-352F3B6F2922&displaylang=en

Also what AV are you running?

Article that might be of assistance to you http://www.eggheadcafe.com/forumarchives/windowsserversbs/Dec2005/post25479514.asp

 

[EasyUp Web Hosting]

AV = Trend. Come to think of it, the problems started about the time I loaded Trend. Previous IT guys never had a AV on the servers and used AVG on the pcs.

Thanx for the link, will check both now.

Edit: Egghead link not really relevant, cause they can still connect to the sbs server and all other networked devices, it's just internet access. Also, I have the preferred DNS as the SBS server.

 

[alchamy]

When a machine can no longer connect to the internet is that including pings and traceroutes? I mean if you compare a traceroute to google from a working machine to one that is not working is there a difference.

Might give you a clue about how deep the problem lies. Also look and see if trend has a log or writes events. It might be creating rules on the fly which is why it works if you change IP.

Also... this

 

[EasyUp Web Hosting]

Can't remember if I did pings or traceroutes, will have to wait for the next pc to give the same problem, so that I can test.

Thanx for the link.