Welcome to Android Central! Which phone? Which Q Link plan do you have? It's possible that with your plan, even though you have unlimited data, the data speed might get throttled after you've used a certain amount of data per month.
Also, does this happen on only on streaming app, or on any streaming app? If it's only one specific one, there could be issues with that service's server.
From their Terms and conditions: "Modifications, Interruptions, or Discontinuation of Data Service: Q LINK Wireless does not guarantee the availability of Data Services on all of its Mobile Device models nor does it guarantee the availability of Data Services at all times. Q LINK Wireless reserves the right to modify, suspend, interrupt, discontinue or permanently cancel Data Services, or portions thereof, without notice. Data Services are not available in certain areas. Q LINK Wireless is not responsible and will not be liable for any modifications, interruptions or discontinuation of the Data Services or for any failure in receipt of the purchased Data Services." https://qlinkwireless.com/terms/