A site-to-site virtual private network (VPN) is a networking setup where two or more networks are privately connected.
Site-to-site VPNs provide an encrypted link between VPN gateways located at each network and ensure encryption in data transfer until the data reaches its destination.
We restrict some DigitalOcean network traffic which prevents functionality like configuring direct server return and using Droplets as routers and site-to-site VPN gateways.