This has been a long and harrowing journey. It started off with trying to connect an RV4042 to a WRV54G, but I was having so much trouble getting that to work that I gave up and went out and bought another RV042, figuring that the same hardware on both ends should simplify matters.
So here's what I'm trying to do for testing purposes:
WRK1 --- VPN1 --- SWITCH --- VPN2 --- WRK2
WAN IP: 22.214.171.124, 255.255.255.0
LAN IP: 192.168.1.1, 255.255.255.0
DHCP'ing: 192.168.1.100-149, 255.255.255.0
WAN IP: 126.96.36.199, 255.255.255.0
LAN IP: 10.4.132.1, 255.255.255.0
DHCP'ing: 10.4.132.100-149, 255.255.255.0
The VPN settings on each are set to point to the other VPN as the Secure Gateway and the other range as the Remote Group (inclusive of the entire range). Changing NO OTHER SETTINGS from the factory default, I press the "connect" button on the VPN Summary page and it says it's connected. Fine so far.
I try from the Diagnostics page on each device to ping the other device. I get no responses from the other device. I disable "Block WAN Request" on each side and I get responses from the WAN IP on each device, but not the LAN IP. Running ping from each workstation produces similar results: I'm able to ping the WAN address of each device, and the LAN address of the local device, but nothing in the other LAN.
As part of my test setup the Default Gateway for each machine is set to 188.8.131.52...meaningless, I believe, since they're both on the same network. If I change the Default Gateway for each to point to the WAN address of the other device then I'm able to ping, map drives, etc, etc, but I realize that this is just ordinary IP traffic that's not being blocked by the normal private-IP-router-blockage because the devices aren't in router mode they're in gateway mode; at any rate, it's not going through the VPN tunnel, because disconnecting the VPN tunnel has no affect on this.
WHAT AM I MISSING? I've contacted LinkSys tech support, who are absolutely no help. (They actually tried to tell me that the devices had to be connected to the Internet, for some unspecified reason. I tried putting one of them at a friend's house, no difference...able to connect the tunnel, unable to communicate through the tunnel.) I've checked, double-checked, and re-double-checked the settings on each device. I'm pulling my hair out. This is supposed to be consumer-level technology, and I, with my gigantic brain and 15-plus years of networking experience can't get it to work, so I presume there is something painfully simple that I'm overlooking. TIA