Gopro consume all trafic

I have a router with two Wi-Fi networks (SSIDs).

When I connect my GoPro to Wi-Fi and it starts uploading footage to the GoPro cloud, the internet in my entire apartment becomes almost unusable. The GoPro seems to consume all available upload bandwidth.

To solve this, I created a second Wi-Fi network on my router and connected only the GoPro to it. I also configured upload and download bandwidth limits for that second Wi-Fi network, while my main Wi-Fi network has no limits.

However, the problem still remains. When the GoPro uploads to the cloud, the internet connection for all my other devices still becomes very slow.

What could be causing this? Is there a better way to limit the GoPro’s bandwidth or prioritize other devices? Should I use QoS, traffic shaping, or another feature?