Code review comment for lp:~hloeung/ubuntu-repository-cache/ipv4-over-ipv6

See Ben's finding where there appears to be network related issues between an AWS region and us - https://pastebin.canonical.com/p/GB5rKBJjsm/

Also from a unit within that same region. IPv4:

| [hloeung@aerodent ~]$ ping -c 5 54.251.159.151
| PING 54.251.159.151 (54.251.159.151) 56(84) bytes of data.
| 64 bytes from 54.251.159.151: icmp_seq=1 ttl=49 time=153 ms
| 64 bytes from 54.251.159.151: icmp_seq=2 ttl=49 time=153 ms
| 64 bytes from 54.251.159.151: icmp_seq=3 ttl=49 time=153 ms
| 64 bytes from 54.251.159.151: icmp_seq=4 ttl=49 time=153 ms
| 64 bytes from 54.251.159.151: icmp_seq=5 ttl=49 time=153 ms
|
| --- 54.251.159.151 ping statistics ---
| 5 packets transmitted, 5 received, 0% packet loss, time 4000ms
| rtt min/avg/max/mdev = 153.173/153.239/153.318/0.354 ms

Now IPv6:

| [hloeung@aerodent ~]$ ping6 -c 5 2406:da18:395:c800:5609:e9e4:9c2d:c153
| PING 2406:da18:395:c800:5609:e9e4:9c2d:c153(2406:da18:395:c800:5609:e9e4:9c2d:c153) 56 data bytes
| 64 bytes from 2406:da18:395:c800:5609:e9e4:9c2d:c153: icmp_seq=1 ttl=240 time=174 ms
| 64 bytes from 2406:da18:395:c800:5609:e9e4:9c2d:c153: icmp_seq=2 ttl=240 time=171 ms
| 64 bytes from 2406:da18:395:c800:5609:e9e4:9c2d:c153: icmp_seq=3 ttl=240 time=171 ms
| 64 bytes from 2406:da18:395:c800:5609:e9e4:9c2d:c153: icmp_seq=4 ttl=240 time=172 ms
| 64 bytes from 2406:da18:395:c800:5609:e9e4:9c2d:c153: icmp_seq=5 ttl=240 time=174 ms
|
| --- 2406:da18:395:c800:5609:e9e4:9c2d:c153 ping statistics ---
| 5 packets transmitted, 5 received, 0% packet loss, time 4004ms
| rtt min/avg/max/mdev = 171.435/172.981/174.714/1.454 ms

That's ~20ms lower via IPv4.