It could be 21.0/8 ref:https://old.reddit.com/r/tmobileisp/comments/1gg7361/why_is_tmobile_giving_network_210008_addresses/ https://old.reddit.com/r/tmobileisp

It could be 21.0/8 ref:https://old.reddit.com/r/tmobileisp/comments/1gg7361/why_is_tmobile_giving_network_210008_addresses/ https://old.reddit.com/r/tmobileisp/comments/1gg7361/why_is_... I booted an LTE router using a T-Mobile SIM. Within an hour I had changed WAN IP. Both were from AS749 US-DOD NIC in 33.79.135.0/24 & 21.140.100.0/24. They were cgnat'd behind TMble's advertised asn.