ER-X L2TP slow connection

I just recently purchased and setup a ER-X using a L2TP VPN server to connect several devices remotely.  I was able to setup the L2TP server successfully using the following guide, but the throughput through the L2TP tunnel is very slow, around 0.50Mbps.  My connection is 75/10 Mbps through Comcast.  This problem is effecting both iOS and Windows clients connecting through the VPN.  Any help would be greatly appreciated.  Below is my L2TP configuration.

 l2tp {
     remote-access {
         authentication {
             local-users {
                 username brice {
                     password xxxxxxx
                 }
             }
             mode local
         }
         client-ip-pool {
             start 192.168.3.200
             stop 192.168.3.205
         }
         dns-servers {
             server-1 208.67.222.222
             server-2 208.67.220.220
         }
         ipsec-settings {
             authentication {
                 mode pre-shared-secret
                 pre-shared-secret 07d6bfd928
             }
             ike-lifetime 3600
         }
         mtu 1492
         outside-address xx.xx.xx.xx
         outside-nexthop xx.xx.xx.xx
     }
 }