While setting up a home office, a technician disables the DHCP service on the office router, but does not want to rely on link-local addressing

You didn't actually ask a question here.

I'm guessing the question is how the home office can still function correctly?

I can see two options:

a) all network clients are configured with their own fixed IP address

b) there is another server than the router that handles DHCP (most NAS devices offer this service as well)