I just implemented your suggestions, and so far so good. It is streaming well now. Edit: Started stuttering again. I will try to implement the below suggestions from Ubiquiti.
Ubiquiti recommended:
"Try the following suggestions and check if it helps
Disable the IPS, IDS, Smart Queues and GeoIP filtering feature from the Unifi controller.
To disable the IPS and IDS options, navigate to Settings>>Threat Management
To disable Smart Queues, navigate to Settings>>Networks>>Edit WAN>> Under Common Settings uncheck Smart Queues
To disable GeoIP Filtering, go to Settings>>Routing & Firewall>>GeoIP Filtering
To disable the BETA GUI, you can navigate to Settings>>System Settings>>New Settings>>Disable>>Apply Changes"