nginx info:client prematurely closed connection

[delleceste]

Hello.
I Use QNetworkAccessManager / QNetworkRequest / QNetworkReply to post a get on a subscriber channel.
By default, the connection is keep alive, but the info message does not change even if I set Connection: close in the header (and in that case, I unexpectedly still receive updates on the channel).
When I decide to quit the application, I close the initial request. From nginx point of view, I am closing a keep alive request prematurely, indeed before receiving one "last" message that finishes the initial request.
I can't find a proper solution to the issue, maybe You have a suggestion.

Sniffing the traffic:

14:01:53.170542 IP 172.20.0.54.59144 > 192.168.205.25.8001: Flags [P.], seq 1:194, ack 1, win 502, options [nop,nop,TS val 1347969617 ecr 3518348859], length 193
E....@@.=.o....6.......A.L.p.=.......$.....
PXbQ...;GET /sub/rchans HTTP/1.1
Host: taeyang.elettra.eu:8001
Accept: text/event-stream
Accept-Encoding: gzip, deflate
Connection: Keep-Alive
Accept-Language: en-US,*
User-Agent: Mozilla/5.0

14:01:53.170822 IP 192.168.205.25.8001 > 172.20.0.54.59144: Flags [P.], seq 1:151, ack 194, win 508, options [nop,nop,TS val 3518348898 ecr 1347969617], length 150
E...T;@[email protected]...=...L.1....:......
...bPXbQHTTP/1.1 200 OK
Server: nginx/1.21.6
Date: Mon, 11 Apr 2022 12:01:53 GMT
Content-Type: text/event-stream; charset=utf-8
Connection: keep-alive

and also the communication close handshake seems to be fine:

14:01:57.224460 IP 172.20.0.54.59144 > 192.168.205.25.8001: Flags [F.], seq 194, ack 1336, win 501, options [nop,nop,TS val 1347973669 ecr 3518351726], length 0

14:01:57.224716 IP 192.168.205.25.8001 > 172.20.0.54.59144: Flags [F.], seq 1336, ack 195, win 508, options [nop,nop,TS val 3518352952 ecr 1347973669], length 0
E..4T?@[email protected]...=...L.2....:3.....
...8PXr%
14:01:57.266741 IP 172.20.0.54.59144 > 192.168.205.25.8001: Flags [.], ack 1337, win 501, options [nop,nop,TS val 1347973713 ecr 3518352952], length 0
E..4.F@.=.pq...6.......A.L.2.=.............
PXrQ...8

NGINX logs:

2022/04/11 14:01:57 [info] 4092415#0: *366 client prematurely closed connection, client: 172.20.0.54, server: taeyang.elettra.eu, request: "GET /sub/rchans HTTP/1.1", host: "taeyang.elettra.eu:8001"

Kind regards.