No devices behind RED 15 can access internet or info on XG side of network

Question

We recently installed our first RED device for a client and have run into some trouble. I've spent considerable time on the phone with support, but we have not been able to crack it. 
 Site #1 - Sophos XG 105 
 Site #2 - Sophos RED 15 
 Both sites have Comcast as the internet provider. 
 When I connect the RED at Site #2, any device connected to it gets it's IP information as defined in the XG. The default gateway that is assigned by DHCP is the IP of the RED device that we set in the XG. However, nothing that is connected behind the RED device can access the internet or any system at Site #1. 
 Any advice or input is greatly appreciated.

Emile Belcourt · Answer

Hi George, 
 As Luk has said about Firewall rules, when creating RED tunnels, you will need to create a firewall rules to allow traffic both ways from RED network to HO LAN and back again, or just create a LAN zone to LAN zone with any service firewall rule will cut it if you bind your RED networks to the LAN zone (I don't like doing that, I put them all on their own RED zone). 
 For connections to WAN, you need to make sure you have a firewall that covers the RED network to WAN with appropriate MASQ rules. 
 What method is your RED tunnel set up to do, Standard/Unified or Standard/Split (assuming Unified as you want connections to the internet routed via XG?) 
 Emile