Endlessly notification. Failed trying to connect to server

Hi,

I recently got a very annoying notification that pops up immediately when my system is rebooting and even before I got my password entered. Then it pops up every 5 minutes or so.

The pop up says:

There was a problem connecting to the server '192.168.178.39'

in Dutch:

That ip adres is from my old windows computer. I had to transfer some files over to my iMac.

I saw some threats on this community with the same problems but the solved answers did't help for me.

I searched the web for anything that could help me stop this notification, or program that causes this notification.

What I know and done so far:

1. I checked if there where any login items under my account. But there where non that are connected to my old system.
2. Deleted the ip adres from favorites in de finder
3. See if there are any start agents that causes the problem.
4. Boot in safe mode. Immediately before entering my password the pop up appeared.
5. I tried some applications that let me see my in and outbound connections. But I really don't know what I am looking for except my server ip adres.

Before all this I recently did a clean install on High Sierra because it supports CUDA. I also installed office from my old computer directly on my Mac over my network. Could that have something to do with it maybe?

I am really desperate.