update to 2020.1 on synology fails

[Rondomoticz]

Help

I have had the 2017 version of domoticz working on my synology (213+ ) for years without problems. After an update of the android app I could not control it anymore with my phone. I read I would probably need an update to domoticz 2020.1.
I tried to install the version from Jadahl, but there things went wrong. Domoticz would not start anymore, all I saw was a blue screen (in the browser).
While trying to get it to work I installed : 2020.1 stable with and without python, the V4 version on Jadahl's page, I upgraded my DSM version to the latest 6.2.3 and tried 2020.1 again.
The best I get is on the "dashboard" tab :
No favorite devices defined ... (Or communication Lost!)
If this is your first time here, please setup your Hardware, and add some Devices.

However nothing happens if I click on Hardware or Devices. Same when I select it from the menu.
The "settings"menu items work, here I have website protection set on " login page" as I read this is important.

I am more of a used of domoticz and not much into the programming and stuff.
Can you suggest how I can get my domoticz to work again?
many many thanks