Not sure what other type of QoS I can implement to improve voice quality - sometimes voice quality is amazing, sometimes it pauses every second

The pauses im assuming is because of jitter? It seems to occur randomly too, sometimes perfectly clear, other times not.

Config:

2 stacked Aruba 3810M switch

Cisco 5512-X firewall -> goes into fortigate firewall provided by ISP which goes into their modem

IP Phones: Hardwired Yealink T46s

Port 1/1 is going from switch to Cisco 5512-X firewall

Cisco QoS

https://pastebin.com/5HQtN67w

Internet is Fiber directly to the building (150/150)

Our ASA also is making a site to site tunnel to our data center, would that affect anything?

VOIP Provider: Ring Central (Cloud hosted)