IPs from subnet can't access SSL connections

[Guest]

[jperello]

Hello

I have over 100 users behind EFW in a high school for content filter purposes and DHCP server.

EFW is as a virtual machine (KVM) in a Proxmox environment. The red interface is configured as a gateway and green with static IP, both are on the same virtual NIC.
The configuration of the firewall port 443 is open from green to red interface.
Network configuration:
192.168.0.0/23
Main gateway 192.168.0.254
EFW working with iface GREEN in both IPs 192.168.0.4 and 192.168.1.4
EFW proxy in transparent mode. There's only one common rule and policy.

So here's the BIG problem
IPs from network 192.168.0.0/24 (hosts configured with netmask 255.255.254.0) can access SSL connections
IPs from network 192.168.1.0/24 (hosts configured with netmask 255.255.254.0) can't access SSL connections

Suspecting from a firewall rule or bug I've disabled any firewall services, but the problem is still there. I've tried too to give internet access from clients  via both IPs of GREEN iface.

I don't understand from where can come the problem.
Can anyone help me?
thanks a lot in advance

Jaume Perelló