Connected to VPN but unable to ping hosts on remote network

I have PC2 connected to a VPN (L2TP/IPsec) server I have setup on R2. I need PC2 to be able to ping PC3 and PC4, but it's not working. When I use a Windows machine to connect to the VPN I can ping hosts under R2, but that is not the case with my Linux machine (Raspbian Jessie). I believe the solution has to do with the routing table but I have no idea what I am doing there. I know that I am connected to R2 from PC2 because when I type 192.168.1.1 into the browser I am greeted with the remote router's login screen. PC2 is 192.168.1.125 under R1, and it is 192.168.1.69 under R2. The public IP for R2 is 76.73.240.120. Here is the current routing information: root@raspberrypi:/home/pi# ip route show default dev ppp0 scope link default via 192.168.1.1 dev wlan0 metric 303 76.73.240.120 via 192.168.1.1 dev wlan0 192.168.1.0/24 dev wlan0 proto kernel scope link src 192.168.1.125 metric 303 192.168.1.1 dev ppp0 proto kernel scope link src 192.168.1.69 What do I need to do in order to get PC2 to be able to ping the hosts under R2?