not talking between subnets

[shallowz]

we have different sites under one domain

site ones address is 100.100.1.1

sites two address is 100.100.2.1

computers in the first site can sync with each other but if a pc from one site tries to sync with a pc in the other site inside the same domain nothing pops up.

[yottabit]

I'm assuming you're using a /24 subnet and not /16?

Okay, so a few things to check. First, can the peers all reach the tracker on the Internet? Make sure it isn't being blocked by your firewall(s).

Second, are your firewalls allowing random outbound ports such as used by BTSync? If your firewall/router is only allowing selective ports to pass between the subnets, note that the clients by default use a random outbound port to relay the transfers through the BT Relay server on the Internet instead of connecting directly to each other.

Third, if your firewall doesn't restrict ports between the subnets, try adding the IP of a peer on the second subnet to a client on the first subnet's Share's Advanced settings. See if the peers directly connect when you do that.