So, ich habe jetzt mal wieder auf Cookie umgestellt und siehe da, sie spricht wieder.
Ich habe dann mal die Debugs zwischen 2FA und Cookie bei TTS miteinander verglichen:
Echo Device (2FA)
SendData | Result: "{"http_code":200,"header":["HTTP\\\/1.1 200 OK\\r","Server: Server\\r","Date: Thu, 27 Jun 2019 11:28:53 GMT\\r","Transfer-Encoding: chunked\\r","Connection: keep-alive\\r","Vary: Content-Type,Accept-Encoding,X-Amzn-CDN-Cache,X-Amzn-AX-Treatment,User-Agent\\r","Content-Encoding: gzip\\r","x-amz-rid: XXX\\r","\\r",""],"body":"HTTP\\\/1.1 0 x-amzn-RequestId: XXX\\r\
Content-Encoding: gzip\\r\
Date: Thu, 27 Jun 2019 11:28:53 GMT\\r\
Connection: close\\r\
\\r\
"}"
Echo Device (Cookie)
SendData | Result: "{"http_code":200,"header":["HTTP\\\/1.1 200 OK\\r","Server: Server\\r","Date: Thu, 27 Jun 2019 11:35:28 GMT\\r","Content-Type: application\\\/json\\r","Content-Length: 20\\r","Connection: keep-alive\\r","x-amzn-RequestId: XXX\\r","Content-Encoding: gzip\\r","x-amz-rid: XXX\\r","Vary: Accept-Encoding,X-Amzn-CDN-Cache,X-Amzn-AX-Treatment,User-Agent\\r","\\r",""],"body":""}"