wifi connections range from excellent to no connection.

I am new to the ORBI LTE world and thought and was told that this device would take the place of my Windstream internet.  However, I have found that the device is not at all reliable.  My connections range between excellent to no connection within seconds, this will last for an entire evening.  This makes streaming videos or attending to Zoom meetings impossible.  I am in an area that has excellent and reliable US Cellular service.  My  Internet Speed tests have been very good, but today - I have 8 MBPS Upload, 78 Ping and O Download  So, what can I do???   Is it the device?  Should I go back to my previous provider?