Wi-Fi to different locations

How can I extend my Wi-Fi signal to different locations like my home office at the other end of my house and also my separate garage? I have Ethernet cable run to each location, but my Xfinity router/moden only has 2 Ethernet ports and I need 1 for my Hue bridge. I do get a Wi-Fi signal to both locations from the router/modem but it’s weak and not very stable. Thanks for any help.