Can't factory reset Samsung Galaxy S20

I'm trying to factory reset a Samsung Galaxy S20 because I've forgotten to add MDM in the initial setup, and as far as I know,w you can't add this later. To do the factory reset, I've done Settings > General Management > Reset > Factory data reset. Then tap Reset and Delete all. But it then asks me to confirm my Samsung Account, which it somehow can't do, because I always get a loading icon that fails after some time. Then it asks me for the password of my Samsung Account, and again goes into a loading icon, which also just stops after some time. I don't get any error message. There's also the option to send a confirmation e-mail, but this also leads to the loading screen, and after some time, I get a little pop-up telling me there is a network error. The screen here stays white, and I need to use the back button to go to the confirmation screen of my Samsung Account. I do have internet access on my phone, because I can open websites with Chrome. I'm using my home Wi-Fi network to connect to the internet. I didn't find any solution to this problem with Google, just the normal documentation from Samsung on how to factory reset a phone, which doesn't work for me.