Synology DSM integration fails to connect with bad header in response

[dglugla]

The problem

When trying to configure a new Synology DSM integration I'm getting "Unable to connect error" constantly.
I created a dedicated HA user in DSM, assigned it to the admins group, and I am able to connect to the DSM from HA via SSH on that user.
In HA logs I found the following error reported:
{'api': None, 'code': -1, 'reason': 'Unknown', 'details': "ClientResponseError = RequestInfo(url=URL('http://my_DSM_host:my_DSM_port/webapi/query.cgi?api=SYNO.API.Info&version=1&method=query'), method='GET', headers=<CIMultiDictProxy('Host': 'my_DSM_host:my_DSM_port', 'User-Agent': 'HomeAssistant/2024.12.5 aiohttp/3.11.11 Python/3.13', 'Accept': '*/*', 'Accept-Encoding': 'gzip, deflate, br')>, real_url=URL('http://my_DSM_host:my_DSM_port/webapi/query.cgi?api=SYNO.API.Info&version=1&method=query'))"}

I tried running this directly from HA's terminal using wget and I got following response from my DSM:
SSH-2.0-OpenSSH_8.2 Invalid SSH identification string.

What version of Home Assistant Core has the issue?

core-2024.12.5

What was the last working version of Home Assistant Core?

No response

What type of installation are you running?

Home Assistant OS

Integration causing the issue

synology_dsm

Link to integration documentation on our website

https://www.home-assistant.io/integrations/synology_dsm

Diagnostics information

No response

Example YAML snippet

No response

Anything in the logs that might be useful for us?

Rejestrator: homeassistant.components.synology_dsm.config_flow
Źródło: components/synology_dsm/config_flow.py:196
integracja: synology_dsm (dokumentacja, Problemy)
Pierwsze zdarzenie: 21 grudnia 2024 23:12:16 (1 zdarzenia)
Ostatnio zalogowany: 21 grudnia 2024 23:12:16

Additional information

No response

[home-assistant]

Hey there @hacf-fr, @Quentame, @mib1185, mind taking a look at this issue as it has been labeled with an integration (synology_dsm) you are listed as a code owner for? Thanks!

Code owner commands

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• @home-assistant close Closes the issue.
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• @home-assistant unassign synology_dsm Removes the current integration label and assignees on the issue, add the integration domain after the command.
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