2.2 firewall dropping packets

[christian]

I know post title is almost similar to this one and I was very tempted to add hereafter question in above post but then I realized it could be somewhat different.
Furthermore none of you reacted to the previous FW related post... 

Here is my point.
On my 2.2 Zentyal server, I've multiple interfaces, 2 are external (failover between 2 ISP) and 2 are internal, one (eth1) for my LAN and one other (eth2) handling my test-bed platforms.

Trying to reach internal (LAN) machine from test-bed, and because it failed despite what I though to be open FW rules, I had a look at syslog on Zentyal server and here is what I can read:

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Feb  4 17:11:21 igws kernel: [  510.113615] ebox-firewall drop IN=eth2 OUT=eth1 SRC=192.168.20.1 DST=192.168.10.12 LEN=60 TOS=0x00 PREC=0x00 TTL=1 ID=62534 PROTO=UDP SPT=49708 DPT=33437 LEN=40 MARK=0x3

Of course, I do have FW rule (in the right section I hope "filtering rules for internal networks) that allows any to any 
No luck...

Any idea ?

I'm going to look closer at iptables but, referring to this post and the previous one (see link above), it sucks