Another option is a separate dedicated device for the vpn, such as a gl.inet mango travel router. They fit in a shirt pocket, run a gl.inet custom version of open-wrt and handle vpn duty like a champ among many other things. It has long been my belief that running a vpn ON the device you are...
Wifi security cameras are very susceptible to packet loss (appears as dropped frames and lag), caused by interference. If you have no wired option with those cameras, you could set channel width to 20mhz, divide the cameras up between different access points on channels 1, 6, 11 the only 2.4ghz...
The ram and cpu utilization when recording your camera streams direct to disk as raw data with no encoding, is very minimal and likely could run at the same time as serving media provided there are dedicated hard drives for each purpose within your htpc. Where the real resource use comes into...
There really needs to be a nvr or dedicated pc to handle the cameras. Trying to serve media on the network while recording HD streams to disk in one machine is not going to do either task well. A pc with Blue Iris (windows) or Agent DVR (Linux or Windows) handling the cameras placed on a...