Thanks to everyone for the assistance. Unfortunately I still can't get any traffic to flow over the VPN. Here is a screenshot showing the server and the client connected to it. But I get no reply when I ping the 10.8.0.1 address.
this is a post I used that was very helpful for me. granted this was a long time ago. a lot of the same issues you describe were flushed out for me in this post. good luck
Okay, here's my procedure. Let me know if there's anything wrong before I start:
1) Log into DD-WRT web interface and perform firmware upgrade with 47581 webflash firmware, without resetting to defaults
2) If all goes well, I can telnet into the router at its current IP address (192.168.1.1) and execute the nvram erase && reboot command
3) Log into the web interface at 192.168.1.1 and provide a new password for DD-WRT
4) Reconfigure the router's WAN and Wifi interfaces, etc
5) If something goes wrong with the flashing process, I can telnet into the router, and run the command
ubootenv set boot_part 1 to go back to the previous 40559 firmware (I have checked that the router is currently on partition 1)
Okay wow, that was easy. I updated the firmware through the web interface, and it went through without a hitch. I did not reset my settings, and so far have experienced no problems. I might do the nvram erase a bit later if I experience any issues.