I have a similar problem. I use a Nextcloud for syncing. This is also added on three Android devices without any problems. Only on my Windows PC the setup of Nextcloud or WEBDAV does not work. As an error I get the message "Could not connect to the specified Nextcloud server". I turned off the Windows firewall briefly and it did not change the problem. I also changed the default browser from Chrome to Edge and this also did nothing. I also tested reinstalling Enpass and the Win10 app. Both brought nothing.
Windows: Windows 10 Home Premium 20H2 Build 19042.1081
AntiVirus: Windows Defender
Firewall: Windows Firewall
Network: All devices are operated in the same network
Windows PC: 6.6.2 (827)
Android Smartphones (Poco F2 Pro and Xiaomi Mi 10): 18.104.22.1680
Android Tablet (Xiaomi MiPad 4): 22.214.171.1240