Site to site IPSEC VPN with different subnets sizes

Question

Hi, how do I setup a site to site IPSEC VPN when one site has a /16 network and the other is a /24? I tried some NAT settings and got side A to ping B but not the reverse.

Site A with /16 has 2 servers that need to communicate with lots of computers on site B with /24. Both sites has a XG firewall.

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Lumbis · Accepted Answer

Solved it. The issue was with one client in our test environment. I just reinstalled that Ubuntu computer and everything worked. The Sophos setup was the same as with normal /24.