Computer make and model? Operating system used? Type of connection? Wireless or wired? Are you using YOUR router/modem in your house to connect to? Or something else? You mention "other devices".. Are they also computer, or are they phones?

You also don't mention what you have tried to fix the problem. Have you tried simply rebooting the computer? If a wireless connection, have you tried disconnecting from the router using the icon in the lower right corner of your screen, then reconnect again.

Tried turning the router/modem off, wait 5 minutes, then turn it on again?

Hope this helps and let us know more.