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…