I have a number of virtual machines running on a very stable Hyper-V 2008 R2 machine. Yesterday’s reboot of my instances to accomodate Windows Update left only my 64-bit Windows 7 instance without a network connection. No amount of fiddling within the instance could restore it. After much frustration I finally removed the Network Adapter from the shut down instance in the Hyper-V Manager and added a new network interface. Upon booting the instance, it installed new drivers and successfully connected to the network.

After struggling for quite some time to discover why the once-working OpenVPN setup on my DD-WRT router suddenly stopped working, I finally realized the configuration was corrupted. I had been issuing a number of iptables commands (inserts and deletes) at the command prompt via ssh prior to the failure, although I do not know if the two are connected.

After disabling the OpenVPN client and rebooting the router, I noticed the Public Client Cert was partially truncated. I pasted the certificates back in, applied changes and rebooted the router and it works again once more.

While attempting to fix the problems in my OpenVPN configuration using DD-WRT on my new router, I connected my laptop to the server, from behind the OpenVPN client machine. I was using it to peer at the OpenVPN logs. Of course, both OpenVPN connections are going to appear from the same address, the laptop behind the NAT router and the router itself so OpenVPN was never going to work for both at the same time. So, the duh tip #2 is to ensure only one OpenVPN connection is made from a single IP address.

My router that ran DD-WRT (WRT54G) died recently and I had temporarily replaced it with my LinkSys VOIP router. I also configured that router to use my dynamic DNS service (DynDNS.org). Upon replacing the broken router with a new one and correctly configuring it, I couldn’t get OpenVPN to work. I finally realized that on the server, when it tried to make the connection back to the client, it was using an IP address from DynDNS.org that was created by the VOIP box that had updated it with a local LAN address. So the tip is, make certain the IP address on the dynamic DNS site is correct – I had to log in and change it by hand because DD-WRT said it didn’t need updating, when in fact it did!