It didn't want to upgrade from 6.47.x to 6.48, first complaining of lack of space.

I tried the free space fix npk.

I tried uploading the new system npk via ftp - although there was a bit more free space reported than the size of the file, it stopped at about 85%. Trying again with overwrite or resume lead to 'unable to write' errors.

I tried using netinstall on a Windows PC and Linux netbook. In both cases, only the router was connected to the PC and only the PC was connected to the port 1 on the router. I tried both holding the reset button down for ages while powering on and using the "/system routerboard settings set boot-device=try-ethernet-once-then-nand" terminal command.

With Windows, despite repeated attempts the router never appeared in the devices available area. (The IP address of the PC was changed per the docs.)

With Linux, the first try produced this:
.. and stayed there until ^C stopped it.

The second try did it as root and did get interesting:
.. until ^C.

That's the right MAC address - does this mean it wasn't really in Etherboot mode or is there some hardware problem with it?

Looking for updates in the router's quick setup page was coming up with errors sounding like 'write failure'...

Just noticed that I had 192.168.0.1 as the ip address with the Linux netinstall.

If I use 192.168.88.1 instead, it's this:
.. with that PXE line repeated about 60 times before it goes silent until I eventually ^C.

With Windows, despite repeated attempts the router never appeared in the devices available area. (The IP address of the PC was changed per the docs.)

It's not clear to me, whether your netinstall was now successful. However, I had the same issues. Unfortunately, I was not able to fix it under Linux but under Windows. So here a few hints:

1. disable all other network connections before running netinstall (even bluetooth)
2. disable Windows firewall
cf. http://alduras.com/wp/mikrotik-netinsta ... res-avoid/

3. Enable the Boot Server in netinstall (net booting) and fill in a corresponding client IP (it is not sufficient only to change the PC's IP)
cf. https://wiki.mikrotik.com/wiki/Manual:Netinstall

3. Enable the Boot Server in netinstall (net booting) and fill in a corresponding client IP (it is not sufficient only to change the PC's IP)

let netinstall first "search" without boot server, and then powering it on