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I've just tried using two different ethernet switches on my network to replace an 8-port Netgear gigabit ethernet switch, which works fine, but doesn't have enough ports for what I need. Computers are connected to a TP-Link TD-8840T router via a switch. They use DHCP for IP address assignment.

One switch is a TigerSwitch 6924M, which I'd expect to be difficult to set up, since it is second hand and has an advanced configuration menu, which I can't access without a serial port. However, the second switch that I tried is a new TP-Link TL-SF024, which doesn't appear to have any configuration options, so that can't be the problem.

When I say "not working," I mean that although they display that they are connected to a network, they cannot access the internet. For example commands like "ping -c10" come up with 100% packet loss.

What could be causing the problem and how do I fix it?

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Can computers on the LAN contact each other through the switch(es)? – Ƭᴇcʜιᴇ007 Sep 21 '12 at 15:45
nmap -sn doesn't reveal any live hosts, which I imagine it should do if the computers can connect to each other through the LAN? – Froskoy Sep 21 '12 at 15:55
Have you just tried pinging other systems/IP addresses on the LAN? – Ƭᴇcʜιᴇ007 Sep 21 '12 at 15:57
Just tried plugging the TL-SF024 in via the Netgear switch and for some reason everything works. I can ping other computers on the network and connect to the internet. Any ideas why this would happen? The TigerSwitch still doesn't work, but I guess I need to set this up more carefully. – Froskoy Sep 21 '12 at 16:22
up vote 0 down vote accepted

Start with basic network troubleshooting:

  • Are all cables connected properly and show link status up?
  • Did the computer receive an IP address from the DHCP server? (ipconfig /all)
  • Can the computer ping other computers on the same switch by IP address?
  • Can the computer ping the router by IP address?
  • Can the computer ping the IP address
  • Does nslookup return a result?
  • Does nslookup NAMESERVER_IP_ADDRESS against each nameserver shown by ipconfig /all return a result?
  • Do problems persist after you deleted the DNS cache? (ipconfig /flushdns)
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Thanks. It now works, but I don't know what the problem was. – Froskoy Sep 23 '12 at 12:50

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