I have ATT U-verse internet service and use their Arris BGW210-700 gateway

One interesting thing is that if I go to the gateway management page, and use their diagnostic tools, I'm able to ping / traceroute the address - but I can't from any devices connected to the gateway

From gateway diag page:

PING 1.1.1.1 (1.1.1.1): 56 data bytes 64 bytes from 1.1.1.1: seq=0 ttl=64 time=0.568 ms 64 bytes from 1.1.1.1: seq=1 ttl=64 time=0.156 ms 64 bytes from 1.1.1.1: seq=2 ttl=64 time=0.164 ms 64 bytes from 1.1.1.1: seq=3 ttl=64 time=0.144 ms

--- 1.1.1.1 ping statistics --- 4 packets transmitted, 4 packets received, 0% packet loss round-trip min/avg/max = 0.144/0.258/0.568 ms

traceroute to 1.1.1.1 (1.1.1.1), 30 hops max, 38 byte packets 1 1dot1dot1dot1.cloudflare-dns.com (1.1.1.1) 0.285 ms 0.177 ms 0.090 ms

The times on the pings make it look like its hitting a loopback address instead. Pings to 8.8.8.8 from the diagnostics page take about 23 ms. No way 1.1.1.1 is completing in under 1ms haha