lynksys
https://www.linksys.com/us/support-article?articleNum=132846
in generale
VPN IPSEC (Virtual Private Network) UDP 500 (+ ip protocol 50 ESP, ip protocol 51 AH)
VPN L2TP (Vpn Layer Two Tunneling Protocol) TCP 1701 (+ UDP 500)
VPN PPTP (Vpn Point-to-Point Tunneling Protocol) TCP 1723 (+ ip protocol 47 GRE)
Microsoft
Configure a Firewall for VPN Traffic
https://technet.microsoft.com/it-it/library/dd458955(v=ws.10).aspx
Simple configuración VPN en Linksys RV042 – YouTube
Howto Linksys
https://www.shrew.net/support/Howto_Linksys