Getting "Connected Without Internet" and "Private DNS Server Cannot Be Accessed" Errors

Hi Team! I keep getting "Connected without internet" wifi status and "Private DNS server cannot be accessed" message on my Samsung Galaxy Note10+ when using NextDNS IPv4 DNS servers on my router. This is the same issue I am gettings when I was still using AdGuard free DNS servers before I switched to NextDNS free service as well. This issue just started today. Is there an issue in the backend? Thank you in advance for your response.