Thanks Linus and Antonio for your replies.
I guess is a driver issue, the thing is that I have been using this exact same configuration in other 10 locations without a problem. It sure is strange.
I don't know if this helps, but I saw this in the log.
Sat Feb 25 17:23:52 2017 kern.info kernel: [21168.652823] batman_adv: bat0: IGMP Querier disappeared - multicast optimizations disabled Sat Feb 25 17:24:02 2017 kern.info kernel: [21178.691583] batman_adv: bat0: IGMP Querier appeared
A quick google search showed that this has to do with multicast, which is disabled in my configuration. Should I enable it?
Also, I have noticed that the node with the issue is constantly requesting who-has the gateway.
I ran this command from the gateway. batctl td -x257 adhoc0
18:23:44.134458 BAT ae:86:74:47:8b:02: BCAST, orig ae:86:74:47:8b:02, seq 1933, ARP, Request who-has 10.10.0.1 tell 10.10.0.142 (ac:86:74:47:8b:00), length 28 18:23:44.145748 BAT ae:86:74:47:8b:02: BCAST, orig ae:86:74:47:8b:02, seq 1933, ARP, Request who-has 10.10.0.1 tell 10.10.0.142 (ac:86:74:47:8b:00), length 28 18:23:45.124692 BAT ae:86:74:47:8b:02: BCAST, orig ae:86:74:47:8b:02, seq 1934, ARP, Request who-has 10.10.0.1 tell 10.10.0.142 (ac:86:74:47:8b:00), length 28 18:23:45.125725 BAT 60:e3:27:f2:71:1c > ae:86:74:47:8b:02: UCAST, ttvn 2, ttl 50, ARP, Reply 10.10.0.1 is-at 6a:64:42:e7:bf:cb, length 28 18:23:45.139625 BAT ae:86:74:47:8b:02: BCAST, orig ae:86:74:47:8b:02, seq 1934, ARP, Request who-has 10.10.0.1 tell 10.10.0.142 (ac:86:74:47:8b:00), length 28 18:23:45.144519 BAT ae:86:74:47:8b:02: BCAST, orig ae:86:74:47:8b:02, seq 1934, ARP, Request who-has 10.10.0.1 tell 10.10.0.142 (ac:86:74:47:8b:00), length 28
Does this means that there is IPv4 transmission?
Is there a way to make sure this is a driver problem?
In the meanwhile I will try a LEDE and a newer Openwrt.
Thanks again for all your help, any comment is welcome.
Best Regards, Derick