does this mean that I don't have to choose 1009 for now, and look for some other model due to some hardware(i assume unidentified) issue?There is no specific list of affected devices. There is a hardware change involved, so software upgrade can't help.
Looks like this is not a hardware issue, so maybe this is linux(kernel or iptables) problem.I've checked on my WAN interface with Wireshark and yes some packets from LAN forwarded to WAN without NAT. ROS 5.19, x86 on Intel Atom DN2800MT.
.254 is my PC which got IP address using DHCP on RB. So there is nothing weird. I have also SIP phone and its packets also I can see with original private IP arrives from ether1(WAN)Also check which device is using .254 and what its IP settings are.