From eScan Wiki
Q. Does eScan updates flow across different networks, sub-networks?
A. Yes, provided you install atleast one eScan Server in each of the other networks OR install the eScan Server on the Gateway PC.
If you have installed eScan Servers on multiple networks, then you should configure one eScan Server as the Master eScan Server. The other eScan Servers can then be configured to pick up their updates from the Master eScan Server.
This will reduce the impact on your Internet connection's bandwidth, and also the load on the main eScan Server.