DNS_PROBE_FINISHED_NXDOMAIN intermittent error

I am getting this error on various occasions sporadically from various devices on my network. This happens to all browsers and is not contained to a specific site. It affects all browsers (Safari, Chrome, Firefox) especially when hitting a search result from google.

I am using an IPfire ditsro as a router for all my devices in my home network having configured nextdns through TLS as follows:

• I know it's not a specific device problem because when I access exactly the same pages through mobile using cellular network I can access them.
• Turning wifi back on the next time I try to access the problem persists.
• When I disable nextdns service and enable Google DNS the problem disappears.
• DNS flushing on a device helps sometimes

This problem appeared a couple of months ago for the first time

Thank you all

Jim