Go to Network setup > QoS > QoS Policy
Select Add entry and configure the following settings:
- Applications > Add a new application
- Choose a name > eg, "VoIPServer"
- LAN > All
- Port range: 5060 to 5061
- Optional: 10000 to 20000 (type: UDP)
- Priority > High
- Marking > Enabled
- CoS > Enabled (value 0)
Submit (to save)
After adding this Quality of Service (QoS) entry, you will then see your full QoS Policy list, which will include the newly created QoS policy.