I have been doing increasingly more work on office and large home networks. Amazing how quickly what seems to be just a few computers can turn out to become quite a network. I just finished a large mansion where the owners had lots of trouble with Sonos, Apple TV, Netflix streaming and sometimes just browsing the internet.
At the end I ended up tracing all the wires to create a map and recreate the network. Replaced the router and switch for more capable models and reorganized the WiFi Access points for a seamless coverage.
Most importantly created easy to understand documentation so the owners or other IT people can ad devices or make changes without causing havoc.
Here is a example for a small office network