We have a pair of FVS318GV2 routers connecting two offices via VPN over cable modems. They both have the latest firmware available. The cable company recently updated the connections to 100Mbps download and 10Mbps upload. However, the best we can get is 50Mbps down and 10Mbps up. This is public connection testing, not through the VPN. The cable company says their modems are working fine and the problem is the VPN. They claim they get full speed when they connect directly to the modems.
