Good morning

I have a router from the Internet Service Provider Huawei, configured with voip on vlan 20 and data on vlan 1, with cisco phones connected, I cannot access the router because I have not been provided with the passwords

So the scenario is
Phones on vlan 20
PC on vlan 1

I have a Tp-Link JetStream 28-Port Gigabit Smart Switch with 24-Port PoE+

TL-SG2428P 4.0

I'm having trouble understanding and configuring the voice vlan

I create vlan 20
I tag the ports where the phones are connected
I enable voice vlan in the QoS menu

When I reboot the switch, I find all ports untagged on vlan 20

Why?

I come from the Cisco world, this is the first time I interact with Tp-Link, I'm having a little difficulty understanding the logic

Thank you so much