ALPN: server did not agree on a protocol. Uses default. - https comunication using pycurl

I need to communicate with a server (on which I cannot act) via APIs thanks to which I can read the status of some requested variables.The APIs are based on POST calls via the HTTPS protocol.The problem is that I need to have a certain communication speed but the session I use for a POST call closes immediately afterwards, forcing me to recreate another one (a procedure that takes about 3 seconds).

I created a function to create a session:

import pycurldef create_session():    session = pycurl.Curl()    session.setopt(session.COOKIEFILE, "")  # Enable cookie handling    session.setopt(session.COOKIEJAR, "cookies.txt")  # Save cookies to a file    session.setopt(session.SSL_VERIFYPEER, 0)  # Disable SSL verification    session.setopt(session.SSL_VERIFYHOST, 0)  # Disable SSL verification    session.setopt(session.VERBOSE, True)  # Enable verbose output for debugging    session.setopt(session.SSL_SESSIONID_CACHE, 1)  # Enable session ID caching    session.setopt(session.HTTP_VERSION, pycurl.CURL_HTTP_VERSION_1_1)    #session.setopt(session.CAINFO, certifi.where())    #session.setopt(session.OPT_CERTINFO, True)    #session.setopt(session.SSL_ENABLE_ALPN, False)    return session

and one for POST:

def post(url, file, header, session):    buffer = BytesIO()    #postfields = urllib.parse.urlencode(file)    session.setopt(session.URL, url)    session.setopt(session.POSTFIELDS, file)    session.setopt(session.HTTPHEADER, [f"{k}: {v}" for k, v in header.items()])    session.setopt(session.WRITEDATA, buffer)    # Add keep-alive header    header['Connection'] = 'keep-alive'    try:        session.perform()        response_code = session.getinfo(pycurl.RESPONSE_CODE)        response_body = buffer.getvalue().decode('utf-8')    except pycurl.error as e:        response_code = None        response_body = f"Request failed: {e}"    return response_body

The log I get is always the following:

*   Trying 172.21.51.191:443...* Connected to 172.21.51.191 (172.21.51.191) port 443* schannel: disabled automatic use of client certificate* schannel: using IP address, SNI is not supported by OS.* ALPN: curl offers http/1.1* ALPN: server did not agree on a protocol. Uses default.* using HTTP/1.x> POST /rest/login.cgi HTTP/1.1Host: 172.21.51.191User-Agent: PycURL/"7.45.3" libcurl/8.6.0-DEV Schannel zlib/1.3.1Accept: */*Content-Type: application/jsonConnection: keep-aliveKeep-Alive: timeout=500.0, max=1000Content-Length: 43< HTTP/1.1 200 OK< Content-Type: application/json; charset=utf-8< Server: embedded HTTPD< Expires: 1 JAN 2013 00:00:00 GMT< Last-Modified: 3 SEP 2024 16:18:28 GMT< Cache-Control: no-cache< Access-Control-Allow-Origin: http://localhost:3000< Last-Modified: 1 JAN 1995 00:00:00 GMT< Transfer-Encoding: chunked< * Leftovers after chunking: 7 bytes* Connection #0 to host 172.21.51.191 left intact*   Trying 172.21.51.191:443...* Connected to 172.21.51.191 (172.21.51.191) port 443* schannel: disabled automatic use of client certificate* schannel: using IP address, SNI is not supported by OS.* ALPN: curl offers http/1.1

Where I note that the HTTP/1.x protocol is used which requires the session to be closed after each call.

I have tried different python libraries but I always have the same problem.What can I do?