I have strange problem with IPv6 address received from DHCP server. Two Pine64+ boards have different IPv4 address but they share the same IPv6 address.
I finally installed Armbian "Focal" to Pine64+ from Kickstarter (board with micro USB power connector). I have two such boards. I connected these to a test network where gateway is OpenWrt 19.07.4; there is DHCP server running on OpenWrt. I do not need IPv6 addresses (I do not have IPv6 connectivity enabled) but these were activated by OpenWrt. Problem is that I have found that both Pine64+ boards receive different IPv4 address but IPv6 address is the same. When I try to connect with ssh client and I use "name" (not IP address), ssh client prefers IPv6 over IPv4 and it always connects to just one board. I needed some time to troubleshoot this "magic", to find that problem is that both boards share the same IPv6 address. I think that source of this problem is that both boards use the same DUID. They have different MAC address but DUID is the same and that is why DHCP server assigns the same IPv6 address to both boards. In my case, it is
IPv6 address: fdf4:26f8:bebb::723
I am not sure how DUID is constructed. Could be this a bug in Armbian? Or is this a problem of Pine64+ hardware? I put my DUID to this post; could you compare with your DUID? Is it the same?? I do not know how to find DUID in Armbian from CLI but I see DUID at DHCP server in the list of active DHCP clients...
I have interesting update to the problem with IPv6 address. I connected Libre LePotato SBC running the same version of Armbian to the same network as Pine64+ but it doesn't receive IPv6 address from DHCP server; it receives only IPv4 address. So it looks like Pine64+ actively asked for IPv6 address (and used the same DUID in the request). Is it possible that image for Potato and Pine64 is configured in different way (dhcpclient)? LePotato board had other problem, two boards had the same IPv4 address, this is because there is no MAC address stored on LePotato board and this is "calculated" and for some reason it was the same on both boards and unique MAC from /file boot/armbianEnv.txt was ignored.
One more update. IPv6 was disabled at LePotato. I enabled it in armbian-config and I see that two LePotato boards share the same IPv6 address!! ;-) Well, it is different address than IPv6 of Pine64 boards but it looks like there is the same problem, that LePotato boards sent the same DUID to DHCP server...
IPv6 address: fdf4:26f8:bebb::c4a