I have tested a way to do remote upgrades of nodes that has worked for me "in the lab".  Here's the scenario I tested:

1) Rocket M2 (device #1) with 1.0.1 firmware and access over mesh to device #3 below.   This is the Target remote node to upgrade.

2) Bullet M2 (device #2) with UBNT factory firmware and configured in wireless settings:

2a) Wireless Mode = "Station"

2b) SSID = "MeshNode"

3) Bullet M2 (device #3) running 1.0.1 firmware with internet gateway and/or attached computer with the 1.1.1 firmware file previously downloaded.

4) Local computer with network cable plugged into device #2 in DHCP mode.  Turn off wireless. (re-purpose computer in #3 at the appropriate step.)

Steps to do remote upgrade (Line of sight sufficient for device #1 and #2 to communicate with each other given conditions and antennas):

1)  Using the computer attached to device #3, remotely access setup of Device #1 and upload and/or download the 1.1.1 firmware version to perform the upgrade.  Device #1 *should* go through full process and reboot with new firmware.  Do "wscan" from Device #3's computer to confirm an SSID of "MeshNode" is showing and the step completed successfully.  

2) Power on Device #2 (re-image device #3 with ubnt factory and configure) and align antenna with Device #1 antenna (still pointing to remote node which is now in AP mode waiting to be configured for the first time).

3) Power on computer and via Device #2 (acting like a layer 2 wifi to lan bridge), your laptop will receive a 192.168.1.x address (from device #1).  

4) browse to "localnode:8080" and perform the setup with callsign, etc. and remotely reboot.

5) Now upgrade local Device #2 to 1.1.1 firmware.

Note, in step 1, I said the node "should" reboot.  When I did this for real on my 5-mile away node, it didn't complete :(, where as in the lab, it did :) .  So no guarantees.

Happy meshing!  73's AE6XE

In theory this should work if you are able to connect to the remote node using the "meshnode" ssid for the setup phase.  If you do not have a direct link then this is not going to work.

I would practice at home before I attempted this.  Worst case is you will have to get close enough to the node to make the  "meshnode" connection.

In my case I have a set of remote nodes that have to go through another set of nodes to get to my QTH.  I can't use this method unless I drive close enough to the distant set of nodes to be able to get the "meshnode" connection.

Also note that if you have multiple nodes at the remote location, you probably want to go to the site anyway to link them together with Ethernet cords.  If you have just two nodes you can tie the lan ports on the poe together.  If you have more than two connect the lan port to a switch (it doesn't have to be a managed switch) or if there is a WRT54 as the site just use the lan ports on it.

The back to back connections dramatically improve the throughput of the node compared to connecting using the wifi.

Clint Anderson, AE5CA