Remote unit update fails

I have a remote unit here that always fails to update. It gets stuck in the update screen when the update progress bar is full and stays there forever. I used the flasher_linux tool to flash it (FRU01211202 loaded automatically by the tool), then connected to wifi, entered the registration key, and then there’s that annoying mandatory additional update (FFSRU02210712) which results in the behavior described above.
Any idea what I can do?

Can you try with another internet?
This sounds link internet connection problem on Herelink controller.

@Alvin thanks for your reply. I tried it now in a different wifi and also with a mobile hotspot, both trials ended up with the same symptoms described above. Any other idea what could cause it?
Is there a way to get the latest firmware and try it with the flasher directly?

Unfortunately the internet update is necessary.
Can you share the ip address when you connect the Herelink to wifi?

what is the origin of this unit? looks like it was provided from an OEM