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The landlord where I live has recently changed ISP, and consequently had to replace their primary modem/router. As I am some distance away I connect through a satellite router which they also set up.

When they changed ISP and router, three PCs running Windows 7 and my Android phone all lost internet connectivity (they connect to the wifi perfectly well, but have no internet access), however two MacBooks that I have tried can both connect flawlessly. Even more baffling I discovered today that my work laptop, running Windows 7 and still showing no internet connection, can establish a VPN through the network to my work perfectly as well!

I am assuming this is some kind of DNS problem, and that the default configuration on OS X has somehow handled the change with ease whereas the Windows and Android config couldn't. None of the systems are using unusual settings - all are connecting using DHCP and their system defaults. There are no IP conflicts that I can see and the satellite router seems to be allocating IP addresses fine.

I have access to the satellite router and all computers and have restarted both that router and the computers multiple times to no avail. I have arranged to go and have a look at the landlord's router (the primary router and modem) tomorrow, but am at a loss for what I am going to look for to begin resolving this.

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As an essential troubleshooting for network, you should try step by step to figure out which is the failure point.

  • Ping/tcp_connect: to verify that you can reach a host or not, sometimes ping maybe blocked so you have to use tcp_connect (netcat,telnet) to the port you acknowledge is opened.
  • Using IP address instead of domainname: to ignore any issue cause by DNS. If you can connect to IP address but not domainname, so you know that cause by DNS.
  • Using traceroute/tracert: try to connect some hosts nearby then go a step further. By this way, you can detect the failure point on the way reaching to destination host. It's a good idea to use tcptrace (Linux) since default trace command use icmp/udp that can be blocked.
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Thanks - it's definitely a DNS error, the satellite router seems to be pointing to the wrong address for DNS, which the MacBooks somehow sensed and bypassed! I should be able to sort this out now I think... – Phueal Feb 23 '14 at 11:38

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