I recently switched my cellular subscription to the Dutch telco Tele2. I noticed I can’t reach 126.96.36.199 on that 4G connection. 188.8.131.52 works though. This is observed on an iPhone, as well as on a desktop that is tethered to the same mobile connection. The desktop is what I used for the manual tests (for output see Pastebin).
Link to test in help tool: https://Cloudflare-dns.com/help#eyJpc0NmIjoiTm8iLCJpc0RvdCI6Ik5vIiwiaXNEb2giOiJObyIsInJlc29sdmVySXAtMS4xLjEuMSI6Ik5vIiwicmVzb2x2ZXJJcC0xLjAuMC4xIjoiWWVzIiwicmVzb2x2ZXJJcC0yNjA2OjQ3MDA6NDcwMDo6MTExMSI6Ik5vIiwicmVzb2x2ZXJJcC0yNjA2OjQ3MDA6NDcwMDo6MTAwMSI6Ik5vIiwiZGF0YWNlbnRlckxvY2F0aW9uIjoiQU1TIiwiaXNwTmFtZSI6IlRlbGUyIE5lZGVybGFuZCIsImlzcEFzbiI6IjEzMTI3In0=