Unable to ping and browse with 1.1.1.1 Cloudflare DNS server

Hi guys,

with my R7500 router if I set 1.1.1.1. as DNS server it is not possible to ping and browse. On the other hand, the secondary of Cloudflare 1.0.0.1 works regularly. Has anyone had the same problem?
I have updated the firmware version to the latest.
Thank you

Piero