Thanks for that very detailed explanation hullray!
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Because what you do in the internet is nobody else business 😎
I found another step-by-step set of instructions online at
http://www.conniq.com/WinXPNetworking_wifi_direct_connection.htm to follow when setting up ad hoc network and internet sharing, so I gave it a try. To make a long story short, I succeeded
once in getting the laptop's ad hoc network to share the VPN connection to the internet via its wireless adapter. I was able to select this ad hoc network on my iPod Touch. Despite many attempts, the Apple TV (2G) device was
never able to recognize the ad hoc network (as it does at my own home with my Mac's ad hoc network), so ultimately the "victory" was hollow. I also could not for the life of me replicate my partial success at will. The ad hoc network would be visible to my iPod but the internet connection would fail even though all seemed to be in order as for set up.
A couple of observations in case they might help others.
1. As you've pointed out, the precise order one does the set-up in XP seems crucial. And at several points in the process, the steps are (to me, not a PC aficionado) not intuitive. For example:
2. When enabling internet connection sharing (ICS) on the VPN connection after setting up the ad hoc network: at the point you go to the Properties>Advanced tab to select the ICS mode, I found I had to FIRST select something like "wireless connection" in the "Home networking connection" choices and only then click on the "Allow other network users to connect through this computer's internet connection" check-box. If I checked on the check box first, I couldn't choose the "Home networking connection" option to be wireless.
3. I then went to the "View available wireless networks" window and disconnected the independent wi-fi router that was also connected to the DSL modem before "connecting" the ad hoc network which also appears in that space.
4. Most interesting/puzzling is what happens when "connecting" the
host computer to the ad hoc network. It seems that the ad hoc network will only be established if another computer or device connects to the ad hoc network broadcast from the host computer. If nothing connects to the broadcast, no "connection" is made, i.e., there is no ad hoc network. In my case, I used my iPod Touch's wi-fi connection settings to connect to the ad hoc network as soon as it appeared as an option. Almost simultaneously on the "host" laptop the ad hoc network changed from "connecting" to "connected" and began to function. If I turned off my iPod Touch, the ad hoc network ceased to exist. In other words, it doesn't seem possible to have the host computer's ad hoc network just broadcasting (as do most wi-fi routers). If nothing connects to the broadcast, the host's attempt to "connect" to the ad hoc network eventually fails (after a few minutes, I think). I find this strange and not very helpful!
5. My final conclusion after all this (for the goal of sharing a VPN connection wirelessly on a PC) is to throw in the towel and get a VPN-enabled wifi router, available, for example at http://strongvpn.com/routers.shtml. And most of the advice on this subject that I've found on the internet implicitly comes to the same conclusion: buy a VPN-enabled router. (And it may be instructive that StrongVPN, one of the better VPN providers, has the same advice and declines to offer advice on ad hoc networks. Admittedly, it sells VPN-enabled routers as part of its business, but StrongVPN is very good at providing tech advice about set-up, so I suspect the frustrations of advising about ad hoc networks led them to that position.)
Thanks for your help and attention.