Help with best setup

Hello, and thank in advance

I currently admin a yeastar s20, 5 softphones, who was used through wifi and had a cracked voice problems, even sometimes (one in ten) call drop

We have an asymmetric 300/30mb fiber internet connection, a Huawei HG8245H 4xRJ45 ports modem/router, no public IP, and under two NATs (one from ISP, and other the HG8245H. Recently add a 8 port smart switch to connect the 5 pc with ethernet because I imagine wifi is loosing packets

S20 with static IP connected to HG8245H, who has DHCP enabled, the switch is connected through port 2 of HG8245H and everything seems working fine, but heres is something strange to me, I can't see the smart switch in the HG8245H even tough I can see the 5 PCs connected and softness works as well. router and switch are on the same network segment

There is a better way to setup the whole system? Maybe connecting the S20 to the switch instead of the router?

I wanted to connect the s20 to the HG8245H via PPPoE but ISP doesn't want me to do it so I configure the static IP

Do I need a better router?
Maybe for bandwidth and Qos control?
HG8245H doesn't seem to have Qos settings, and all common ports seem closed and unable to open them

I looking for another internet provider. 300/30mb works well, but closed ports doesn't let me have remote extensions and sometime the call drops, don't figure out yet if is because lack of router/bandwidth control, Qos setting in the router, although QoS is configured on the s20, (and even in wirehairs it seems the SIP protocol has the right priority)

Thank you very much for your advice