Linux.com - https://www.linux.com/news/set-raspberry-pi-wireless-access-point
Set up a wireless access point with a Raspberry Pi 3, Ubuntu Core, and snaps.
Router coverage gaps often have different causes, which repeaters and access points (APs) can remedy. A repeater usually connects to the router over WiFi and amplifies the signal into areas where the router alone is not sufficient, whereas an AP wired to the router by cable sets up a private WiFi network with its own network identifier (SSID). The AP therefore provides additional access to the local network.