OpenVPN tunnel keeps restarting

I have two ERX SFPs connected via OpenVPN tunnel. Like clockwork, every couple minutes they break the connection and restart it. I gather it's from my keepalive 10 60 directive, but I don't know why they would so regularly drop the connection. Any ideas?

This is the client router's config:

david@ubnt# show interfaces openvpn vtun1
 encryption aes256
 mode client
 openvpn-option --comp-lzo
 openvpn-option "--keepalive 10 60"
 protocol udp
 remote-host xyz.com
 remote-port 1194
 tls {
     ca-cert-file /config/auth/openvpn/Meadows/ca.crt
     cert-file /config/auth/openvpn/Meadows/dave.crt
     key-file /config/auth/openvpn/Meadows/dave.key
 }

This is the server router's config:

david@ubnt# show interfaces openvpn vtun0
 encryption aes256
 mode server
 openvpn-option --client-to-client
 openvpn-option --comp-lzo
 server {
     client dave {
         subnet 192.168.4.0/24
     }
     client parents {
         subnet 192.168.1.0/24
     }
     push-route 192.168.3.0/24
     subnet 10.9.0.0/24
 }
 tls {
     ca-cert-file /config/auth/openvpn/server1/ca.crt
     cert-file /config/auth/openvpn/server1/MeadowsRouter.crt
     dh-file /config/auth/openvpn/server1/dh.pem
     key-file /config/auth/openvpn/server1/MeadowsRouter.key
 }

The ERX SFP that is the OpenVPN server has an additional client: the Tomato router at my parents' house. It's worth noting that the tunnel between the Tomato router and the server ERXSFP is stable. It's just the tunnel between the two ERX SFPs that restarts every couple minutes.

Thanks for any ideas.