TS Port server 8/16

we are using TS port server at remote store over a VPN Tunnel. The Main Store has a SCO-UNIX server. when we switch the VPN Router from a Linksys BEFVP41 router to a Multitech RF560VPN the connect over the port server is slow, but the connection over Networked PC are faster.
We are using the software from Digi on the SCO-unix server. Help!

Be sure you are using the latest SCO OpenServer RealPort driver release, along with applying the WAN link speed setting to accommodate the VPN speed. Otherwise, the driver will communicate at LAN speeds (10/100 Mbps).