OTA doesn't finish the upload

[Atalaya]

Good afternoon
I've had OTA working in the past so now I'm stumped as to why it's not working.
So, I used the IDF example "native_ota_example" code to go back to basics, which gives the same result as my project code.

Environment is Eclipse with ESP-IDF 4.3.3

... and I've just ascertained that with the example code, after initiating the OTA update,
- wait a reasonable amount of seconds
- then kill the openssl process on the remote server and the update works....

Is there a fix for this situation? I don't want to be in attendance every time a client needs to do a firmware update.

Thanks in advance.