Client auto discovery fails, PC goes offline if name removed from Hints section

I’d use the “Internet” mode (clients connect to server).

For importing clients to hints section programmatically see e.g. https://github.com/uroni/urbackup-server-python-web-api-wrapper/blob/master/test/urbackup_api_test.py#L13

That is via python:

server = urbackup_api.urbackup_server("http://127.0.0.1:55414/x", "admin", "foo")
computernames = """2.2.2.2
3.3.3.3"""
for line in computernames:
    server.add_extra_client(line)

Computernames could e.g. be read from a file or listed by some other method…