EPL Link working only 1 way

Hello folks,

I've been working for a while on this configuration but I can't seem to make it work somehow. I am totally alone trying to make it work and I need help. Thanks in advance for your input. Basically, EPL is like a very long cable and it seemed easy to setup but i'm stuck. Here is the topology:https://imgur.com/gallery/aPKyeJQ

On site B, I can reach a server in the 10.37.20.0/24 network from the 192.168.100.0/24 network but I can't reach anything from site A to anything in site B. There's an address object group including the lan networks from site A including 10.37.100.0/29. There's also a routing policy from X0 to X3.

Even though I looked through the Meraki documentation, I haven't found anything related to an EPL connection or routing to non-meraki router. There are mostly MPLS or VPN walkthrough. There's a routing subnet from the L3 switch MS250-48. If I create a DHCP server in the 10.37.100.0/29 network and plug my PC in in site B, I get an dhcp IP and can reach everything in the site A. It seems the rest of the Routing configuration that I found can be done on the firewall side in "adressing and VLANS" but in order to maximize the bandwidth I'd like not to use the MX if possible.

So, what I am missing? any idea is welcome!