Dear radule!
You need to cover two floors with wireless signals. It is recommended that two Wi-Fi signal sources be set up. One Wi-Fi signal source is from the SSID of the HG8245Q2, and the other is from the original wireless router. The original wireless router is connected to the HG8245Q2 through a network cable.
You say you don't have any internet on your second (new) wifi. The possible cause is that the second SSID is not activated.
See the following figure:

Therefore, you need to activate the corresponding port(Select the port and click Apply).
Why IPTV and Internet access services are transmitted through different LAN ports depends on the ISP configuration in the central equipment room,
If the two types of services are configured in the same VLAN, you can receive the two types of service signals on one LAN port. However, they well affect each other. When you download HD movies, if the bandwidth is low, the IPTV service is affected and the TV signals are not smooth.
If the two types of services are configured in different VLANs, you need to receive the service signals from the two LAN ports. In this way, the two types of services do not affect each other. When you download HD movies, if the bandwidth is small, the IPTV service is not affected and you can watch TV normally.
For more information: https://support.huawei.com/enterprise/en/access-network/echolife-hg8245q2-pid-21989531
I hope my answer can help you. Thank you!