But does someone have experience with setting up a second network (one with WEP or no encryption) within the same subnet as one secured with WPA2? Is it even possible? You need 2 DHCP servers with non-overlapping ranges? Or can computers see each other on separate subnets somehow? All online guides recommend only using one DHCP server, but I suppose most don't have to deal with using WEP in year 2015.
I have two wireless routers in my setup, a main router as a gateway to the outside internet which also provides wireless WPA2 access, and then another one just for Amiga usage with WEP.
The WEP one is connected to the same LAN with others (no WAN connection at all on it) and I have disabled DHCP server on it. I haven't even tried if Amigas would get addresses with DHCP from the other router, I guess they should, because AFAIK DHCP client finds the server with broadcasting.. but using static addresses is easier with Amiga anyway.
So, all devices are happily in the same LAN/subnet on my system, but I usually keep the WEP router off and only turn it on on the rare occasions I need to get online with my wireless Amigas. It's still not the most secure way, but at least much better than having WEP available all the time. I guess you could make them to different subnets for more security and then have port forwarding for the services you want to share locally...