You can still access the web interface of the slave node to do the upgrade.
The 2.x version used to clearly state the slave IP, this is something they probably need to add back in the mesh menu. You should be able to see the MAC of the subnode in the mesh menu (master node) and then if you go to the clients menu you can find the matching IP.
From that you can access the web interface and update as normal.
It may also be worthwhile using luci to set a DHCP reservation for your slave node so you always know the IP.
Master not upgrading slave
2 No web interface on slave
I don’t want to muck around too much with it after the problems getting mesh working. Can I just use SCP to download the .Img file and use sysupgrade via SSH?
As I say mesh is working but I would like same firmware on both nodes easiest way possible.
Got some time to play. I SSHed to the slave node, restarted uhttpd and now when I use the browser to point towards the node and I got the Luci interface. That’s one better. Did the 3.025 firmware update via Luci and all went well!
After a reboot now if I got to 192.168.8.2 (slave node), I get the Gl.Inet web interface but it tells me that the password or username is wrong?!? If I got to 192.168.8.2\cgi-bin\luci I get the Luci interface which I can log into with my standard password and the password also works for SSH and WinSCP sessions.
I do have two nodes running 3.025, mesh running fine!