Hi sifus

I have an issue here:

Newly subscribed to UNIFI 500Mbps
2 in 1 Modem Router provided: Fiberhome Combo box AX3000
Own router: TP-Link Wifi 7 BE400

1. Connect the Unifi modem router, Login to 192.168.0.1
2. Change the Unifi modem router to Bridge mode
3. Make sure the LAN Port 1 from the Unifi Modem/Router is connected to the TPLink BE400 WAN port.
4. Reset the TP-Link router
5. Connect the TP-Link router and Login in to 192.168.0.1.
6. Set up the PPPoE ID and Password following the Unifi router.
7. Changed my tplink's IPTV/VLAN to Mode: Malaysia Unifi
8. Managed to get internet, but the top speed is about 90Mbps only

Which part could be wrong?
Troubleshoot tried:
- Change to a different Ethernet cable
- Switch off TP-Link auto traffic control
- Reset and set up all over again

Before adding the router, directly connecting to the fiberhome modem router can get up to 500Mbps, 5GHz, and stand beside it