Correct, that'll give you 192.168.0.0 - 192.168.3.255 . Just make sure you then change the netmask on all the existing devices as well, otherwise they won't see the new ones properly, and vice versa. Windows has its caring tendency to automatically fill it in as 255.255.255.0, which is nice, but potentially annoying.
You won't need to change your router's IP (I'm guessing 192.168.1.1 or .254?), that'll keep working just fine with the new subnet.
Thanks. Yeah, I'll just power cycle everything that needs it and tweak a few static IPs. I /think/ most are dished out as static by the router itself defined my MACs, but I'm sure I've got a few that a proper manual.
It's mainly because I'm going to making use of a number of ESP8266 devices and it would be nice to have them organised together in a separate range.
I'll hopefully be removing one RPi from my setup and replacing it with an ESP8266 at some point once I paint my desk and get my "office" back in working order.
Dunno if this helps, but my wifi router does 192.168.2.x, and my tablet can see local webserver @ 192.168.1.x (wifi & server both to same wired router)
driver killed while using autopilot was watching Harry Potter