RealVNC Enterprise5.3 or later

RFB 005.000

VNC:
  Protocol Version: 5.0
  Security Types:
    5: RA2
    13: RealVNC
    129: Tight Unix Login Authentication
    133: RealVNC

HTTP/1.1 503 Service Unavailable
Content-Type: text/html; charset=us-ascii
Server: Microsoft-HTTPAPI/2.0
Date: Fri, 10 May 2024 04:58:20 GMT
Connection: close
Content-Length: 326

HTTP/1.1 400 Bad Request
Server: squid/3.5.12
Mime-Version: 1.0
Date: Tue, 30 Apr 2024 16:04:07 GMT
Content-Type: text/html;charset=utf-8
Content-Length: 3533
X-Squid-Error: ERR_INVALID_URL 0
Vary: Accept-Language
Content-Language: en
X-Cache: MISS from IPRENT.CN
X-Cache-Lookup: NONE from IPRENT.CN:6666
Via: 1.1 IPRENT.CN (squid/3.5.12)
Connection: close