Intermittent internet loss

Hey folks. I was looking at a LAN setup that a friend of mine has at his work. It consists of a DSL modem, connected to a D-Link router, then the router to a 24 (or so) port switch. There are about 12-15 computers attached to the switch. What is happening with their system recently, is that some of the computers will randomly lose their net connection. They are still connected to the network, but have no internet. This will last for an undetermined amount of time, usually an hour or so, then the net will come back up, and different computers on the network will lose their connection. This cycle goes on and on. I refreshed the router settings using the button (not the reset, but the refresh) on the router, and that seemed to clear up the problem. But the next day, same thing. When they are losing their connection, there is no Default Gateway listed in ipconfig. The Windows troubleshooter is unable to resolve the problem, it says no default gateway available. Any thoughts?

 

ISP says everything is good on their end. Switch is where I'll look into next.

 

My top solutions:
changing to static ip's on the network
Upgrading to a business class router

What is the purpose of the D-Link besides using it as a DHCP server? If you switch the network to static settings, you wouldn't need the D-Link if that is all it is doing. Eliminates a piece of hardware that can fail.

 

If you switch to static settings, I suggest a system for the IP's. I started with 5 users, now I have over 50 so I'm glad I made the system early.

Example:

Firewall and all related:
192.168.28.1 - 9

VOIP phone / VM
192.168.28.10 - 19

Owners:
192.168.28.20 - 29

Accounting:
192.168.28.30 - 49

Sales:
192.168.28.50 - 79

Shipping:
192.168.28.80 - 89

Reserve:
192.168.28.90 - 99

Servers:
192.168.28.100 - 119

The networked print servers go along with the pattern by being located at the 1XX area of the related group. I.E. Accounting person with 192.168.28.33 has a networked printer at 192.168.28.133. If I'm 192.168.28.27, my printer is .127, the wireless router I temp added to my office for a conference was .227. It makes it easy for me to identify traffic.

Added bonus is that I give someone like the phone vendor a block of available IP's and tape a paper to wall in the phone room for him to keep track what he is using. If he messes up, he only makes IP conflicts for his own system, he doesn't (usually) mess up users on the network.


I highly recommend staying away from the very common schemes of 192.168.0.X or 192.168.1.X

 

It sounds to me like DHCP isn't working right and you have more computers than you do IP addresses. Log into the D Link and see what your scope is for your IP addresses.