Upsteam dependency error, code 400 when trying to connect with web player

[yomomma2]

Plan

Premium

Country

Poland

Device

PC

Operating System

Windows 10

After successfully obtaining the auth token and creating a player instance in my web app, I keep getting this network error when I call player.connect():

Request:

Request URL:
https://cpapi.spotify.com/v1/client/some-id
Request Method:
PUT
Status Code:
400

Response:

{
  "code": 3,
  "message": "upstream dependency failed: DeviceCapabilitiesClient client; (400) Bad Request",
  "details": []
}

I've tried on Chrome and Firefox, with all extensions disabled.

I couldn't find any information about this particular error on the internet. What am I doing wrong?