Battery drains faster when connected to certain WiFi routers

For many months the battery sometimes drains quite quickly. I hoped iodéOS-updates may address the problem but I am up-to-date and it is still the same. It seems that the relatively fast battery drainage only happens when the phone is connected to certain Wi-Fi routers. I tried the tips from this thread. But unfortunately they don’t help with my problem.
When there is no Wifi connection and when the phone is connected to the internet with mobile data (LTE) and to certain WiFi-routers, there is no problem. But while being connected to certain Wifi routers, the battery drains quicker than usual. I tried to find out what kind of router or setting causes the battery drainage but was not yet successful.
Is there anybody with a tip or can help to investigate the problem?

2,4 or 5 GHz Band?
Roaming or no Roaming?
Weak signal?
all aspects that need to be included. You can’t generalize anything here.
WiFi is the work of the devil

@AlphaElwedritsch Thank you for your post and questions!

  • 2,4 or 5 GHz Band? I tried both of them.
  • Roaming or no Roaming? There is only one router.
  • Weak signal? Maybe but it also drains fairly fast when I am close to the router. I have had different phones with LineageOS and /e/ in the same Wi-Fi network without the battery drainage issue.
  • All aspects that need to be included. - Yes!

Testing all possible WiFi-settings on my router and device did not help anything incl. WiFi4 instead of WiFi6, 2,4 or 5 Ghz.
iodé showed me the running background apps at some point (out of the blue) and I started turning off one by one. It looks like the beloved KDEConnect app is the culprit for the battery draining on my device. I have not had any issues with it on other devices so far and the percentage of battery use for the app is low. Therefore, I was surprised. But after “force stop” within the “App info” the battery life is much better. This is a pity as I have used KDEConnect regularly.
There is already a bug report for it:
KDE Connect is draining battery — 442782 – KDE Connect is draining battery
Hopefully this can be fixed.