Firefox connection refused

[roman4e]

Firefox connection is refused due to some header missing?
There are generic Request headers from the latest FF:

GET /sip HTTP/1.1
Host: localhost:5080
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:70.0) Gecko/20100101 Firefox/70.0
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Sec-WebSocket-Version: 13
Origin: http://localhost:8000
Sec-WebSocket-Protocol: sip
Sec-WebSocket-Extensions: permessage-deflate
Sec-WebSocket-Key: VUF5UUwgjXPAhr6eiBLdFQ==
Connection: keep-alive, Upgrade
Pragma: no-cache
Cache-Control: no-cache
Upgrade: websocket

And there is an Answer from rtclite:

19:04:46.988 sip.api DEBUG - ('127.0.0.1', 5080)=>('127.0.0.1', 60330)
HTTP/1.1 400 Bad Request
Content-Length: 36
Content-Type: text/plain

missing or invalid Connection header

The only difference to Chrome in these two headers:

Connection: Upgrade
Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits

and Firefox:

Connection: keep-alive, Upgrade
Sec-WebSocket-Extensions: permessage-deflate

Could Keep-alive be a reason?

[ROBERT-MCDOWELL]

you must connect with https, not choice