Synology DSM integration fails after restart and cannot be re-added (TimeoutError / runtime_data)

The problem

The Synology DSM integration initially worked correctly.

After restarting Home Assistant, all Synology entities became unavailable.

The integration showed:
“Setup failed, will retry: TimeoutError”

I then removed the integration and tried to add it again.

Now adding the integration no longer completes. After entering the credentials and clicking submit, the spinner runs for a while and then stops without creating the integration.

Logs show:

Logger: homeassistant.components.synology_dsm.config_flow

{‘api’: None, ‘code’: -1, ‘reason’: ‘Unknown’, ‘details’: ‘TimeoutError’}

Earlier, while the existing config entry was still present, I also received:

AttributeError: ‘ConfigEntry’ object has no attribute ‘runtime_data’

at:
homeassistant/components/synology_dsm/config_flow.py

Environment

Home Assistant OS
Core: 2026.8.2
Supervisor: 2026.07.5
Operating System: 18.2
Frontend: 20260729.7

Synology:
DS213j
DSM 7.1.1-42962 Update 9

NAS IP:
192.168.1.54

Connection settings tested:
HTTPS
Port 5001
SSL enabled
Certificate verification disabled

Authentication tested with:

  • existing admin account
  • dedicated homeassistant account with administrator permissions

Both produce the same TimeoutError.

Network/API verification

The NAS itself is fully reachable and DSM works normally.

The Synology API responds successfully:

curl -k “https://192.168.1.54:5001/webapi/query.cgi?api=SYNO.API.Info&version=1&method=query&query=SYNO.API.Auth

returns:

{“data”:{“SYNO.API.Auth”:{“maxVersion”:7,“minVersion”:1,“path”:“entry.cgi”}},“success”:true}

HTTPS response time is also normal:

curl -k “https://192.168.1.54:5001

~0.7 seconds total.

Therefore the NAS is reachable and its API responds normally.

Additional information

The integration worked correctly before restarting Home Assistant.

After the restart:

  • all previously created entities became unavailable
  • setup started timing out
  • after removing the integration it can no longer be added again

No configuration changes were made on the Synology before the problem appeared.

Has the IP address changed?
Did you set static addresses in the router so they don’t?

No, I changed nothing. Tried to integrate again (after deleting) without any chance. I see the synology and HA tells me to integrate but fails.

DHCP can change IP addresses whenever it wants to. You don’t have to tell it to.
This is why you lock it down.
I suggest you check that the IP addresses that you set when it was working are same ones that these devices responds to now.