Http integration through proxy server

Hi, my loraserver is behind a company proxy server in DMZ. http integration to an external endpoint fails with i/o timeout.

Aug 09 08:50:38 lns lora-app-server[959]: time="2019-08-09T08:50:38Z" level=error msg="integration/multi: integration *http.Integration error" error="send error: http request error: Post https://165.227.143.146/NOZWxp9MBRhPwPpMy6KJ: dial tcp 165.227.143.146:443: i/o timeout"

http connections from the OS work through proxy without problems.

loraadmin@lns:~$ wget https://165.227.143.146/NOZWxp9MBRhPwPpMy6KJ --no-check-certificate
--2019-08-09 08:51:43--  https://165.227.143.146/NOZWxp9MBRhPwPpMy6KJ
Connecting to 192.168.160.20:9090... connected.
    WARNING: certificate common name ‘*.hookbin.com’ doesn't match requested host name ‘165.227.143.146’.
Proxy request sent, awaiting response... 200 OK

i tested with IP addresses to exclude any problems with DNS resolving.

Is there any chance to get this to work?