Ping lite in action
Network problems can be hard to get fixed if you do not know the error source. But there are always nifty tricks to reach the goal. For the iPhone there is a little free and powerful suite helping you out with networking.
Ping Lite helps offers you Pings, Subnet Pings, Traceroute and Telnet.
The coolest in my opinion is the subnet ping.
It shows you all endings from 0 to 255. Then it makes a ping to the first. If there was an answer it will be marked green. Now, going to the next looping doing the same. So it is very easy to find how many and which IPs are used.
These tools are working all the time, even having WIFI disabled.
A useful example is when you try to open website or to reach a special server from your network, but anyhow this does not work. Make sure, your iPhone is not using the same network connection, so just disable WIFI. Then ping that website from your iPhone. If that works on the iPhone and not on your local network, then you certainly know, there is an issue. Commonly a reboot of the router will help.