Ensure your smartphone (from which you're sharing the hotspot connection) is connected to the internet, your data package hasn't expired, and the hotspot is enabled on your phone.
Stop your device from connecting to other networks. To do that, go to Settings > Network and Internet > Wi-Fi > Show Available Networks. Expand each available network, click on the "ⓘ" symbol, and uncheck the box next to "Connect Automatically When in Range".
Try forgetting other available networks except for your primary hotspot connection. Go to Settings > Network and Internet > Wi-Fi > Manage Known Networks. Then, click the "Forget" button next to each network, leaving only the one you intend to use.
