Routing traffic across 2 subnets and 2 ports but over the same LAN Zone

You need a LAN to LAN rule in Case you have multiple Interfaces in the same Zone. 

Without LAN to LAN, the XG will drop the traffic because no matching rule applies. 

Forgot to ask: 

Which traffic do you want to allow? Some kind of protocols uses broadcast and are not routeable. 

I have a LAN to LAN rule for every Service but it doesn't allow traffic to flow.

I can't access my fileserver or use RDP except ping / nslookup because I made separate rules for icmp /dns requests.

Also, my wireless Network doesn't get recognized as a Domain Network, which could be the cause of the above mentioned Errors.

Could you perform a tcpdump on CLI? 

Advanced Shell (SSH Port 22 - 5 - 3).

tcpdump -ni any port 389 

And try to reach the RDP again.