生产环境SONOS Control API订阅事件返回403禁止访问错误求助

生产代码已超过一年未进行修改，当前在订阅Sonos Control事件时出现问题：Sonos Web服务器返回403（访问被拒绝）错误。例如调用订阅播放元数据的接口：https://api.ws.sonos.com/control/api/v1/groups/RINCON_xxx:yyy/playbackMetadata/subscription，返回如下错误信息：

System.Net.WebException: The remote server returned an error: (403) Forbidden.
   at System.Net.HttpWebRequest.GetResponse()
   at CT.Sonos.Control.SonosControlApi.GetResponse(HttpWebRequest request)

CT.Sonos.Control.SonosControlApi: 2023-03-30 11:34:52,128 [44] ERROR TransactJson: POST https://api.ws.sonos.com/control/api/v1/groups/RINCON_xxx:yyy/playbackMetadata/subscription content=[] : re_entrant=False, ErrorCode=[BAD_JSON_RESPONSE], Reason=[<HTML><HEAD>
<TITLE>Access Denied</TITLE>
</HEAD><BODY>
<H1>Access Denied</H1>
 
You don't have permission to access "http&#58;&#47;&#47;api&#46;ws&#46;sonos&#46;com&#47;control&#47;api&#47;v1&#47;groups&#47;RINCON&#RINCON_xxx:yyy#47;playbackMetadata&#47;subscription" on this server.<P>
Reference&#32;&#35;18&#46;27761cb8&#46;1680190492&#46;2d72611
</BODY>
</HTML>
], X-Sonos-Type=[]

注：已移除消息中的设备信息

内容的提问来源于stack exchange，提问作者Krinkster