LAN connection still active but internet drops intermittently for no reason, still able to ping local network

[tuxedy]

Hello everyone, I've got a nagging problem. I'm currently working abroad in Africa as a dentist with absolutely no competent IT personnel.

I have a Windows XP computer acting as a server for my images connected to an old x-ray machine that will only work with XP. It has been working like a charm for the last year but in the last week or so, we've had problems with it. For no apparent reason, the other computers on the network can't communicate with the server (sql). They are able to ping the machine but can't communicate. Even the server itself can't connect to its own database. What I have noticed is that at the same time there is no internet connection on the server machine anymore. LAN looks active, pings local network fine, but unable to communicate outside.

I took off LAN power hibernation option to keep always on, that helped for some time I thought but I don't think it truly has.

I am running Kaspersky Internet Security and Windows Firewall. I have tried taking down firewall or adding exceptions and it doesn't seem to be related to the issue. Does anyone have any ideas or things I can do to test when the connection is down? I have an IT support person in Korea but they need to use teamviewer to see the problem, but they can't because when the problem is happening Teamviewer can't even work as there is no internet connection.

Would appreciate any help!

 

[DelJo63]

Can you describe how the equipment is wired from the internet coming in, thru every box up to the last one?

 

[tuxedy]

I've noticed today that the server can intermittently ping other computers while the internet is down, sometimes the other computers can ping it, sometimes they can.t

Fiber into Router
Router into Main switch - which main server is on
Main switch into local switch
Local server and all connected LAN computers in clinic connected to local switch
All dhcp is provided by main router.
Our local switch also has a router that provides own dhcp, but that's only for wireless connections for phones, etc.

 

[tuxedy]

The only problem that is happening is on the local server. All other computers get internet, communicate with one another no problem. In fact one other clinic computer has a server for another imaging software. But there are no problems there.

 

[DelJo63]

Our local switch also has a router that provides own dhcp, but that's only for wireless connections for phones, etc.

hmm; likely a point of contention and that's a mistake.

I assume that ALL devices have addresses related to the main gateway router,
say 192.168.1.x (aka subnet)
If you have more that one subnet, then while it is possible, the routing tables need manual adjustment.

Using ONE DHCP, use reserved addresses to for groups, x.x.1.2-100 Main, 101-150 as wifi
(each reserve takes the Mac addr->reserves a specific IP address)

Then if necessary, the routing tables and/or the firewall can be adjusted.

 

[tuxedy]

Thank you for your help. I discovered the problem.

My server computer had as its local host 127.0.0.1. I also had an outdated filtering software called K9 Web Protection that would use the local server to filter out any questionable sites, however it seemed to go down sporatically without any notice or error codes and would stop all content going in and out. Once I deleted that web protection the problems appeared to have gone away. Will post if anything changes.