Hi,
One of the option is to use router's Web filter feature, which will allow to block specific streaming website like youtube, netflix, hulu and etc.
More information about that could be found in teltonika wiki
You can take Jerome's example for blocking youtube.
Other option could be blocking specific ports on the router using firewall rules, which are used by streaming services.
Here you can find additional information regarding firewall rules. For ports, which should be blocked, you should be able to find information online for different streaming service providers