Confermo pure che la rete funziona con la MTU della PPPoE a 1500:
matteo@turbo:~$ ping -nc4 -Mdo -s1472 www.google.com
PING www.google.com (216.58.205.36) 1472(1500) bytes of data.
1480 bytes from 216.58.205.36: icmp_seq=1 ttl=115 time=9.32 ms
1480 bytes from 216.58.205.36: icmp_seq=2 ttl=115 time=4.00 ms
1480 bytes from 216.58.205.36: icmp_seq=3 ttl=115 time=3.69 ms
1480 bytes from 216.58.205.36: icmp_seq=4 ttl=115 time=3.99 ms
--- www.google.com ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3005ms
rtt min/avg/max/mdev = 3.694/5.249/9.318/2.352 ms
matteo@turbo:~$ ping -nc4 -Mdo -s1472 www.cloudflare.com
PING www.cloudflare.com (104.16.124.96) 1472(1500) bytes of data.
1480 bytes from 104.16.124.96: icmp_seq=1 ttl=55 time=10.7 ms
1480 bytes from 104.16.124.96: icmp_seq=2 ttl=55 time=3.98 ms
1480 bytes from 104.16.124.96: icmp_seq=3 ttl=55 time=12.5 ms
1480 bytes from 104.16.124.96: icmp_seq=4 ttl=55 time=4.17 ms
--- www.cloudflare.com ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3004ms
rtt min/avg/max/mdev = 3.982/7.833/12.529/3.817 ms
matteo@turbo:~$ ping -nc4 -Mdo -s1472 www.microsoft.com
PING e13678.dscb.akamaiedge.net (2.22.33.235) 1472(1500) bytes of data.
1480 bytes from 2.22.33.235: icmp_seq=1 ttl=57 time=12.5 ms
1480 bytes from 2.22.33.235: icmp_seq=2 ttl=57 time=12.2 ms
1480 bytes from 2.22.33.235: icmp_seq=3 ttl=57 time=3.43 ms
1480 bytes from 2.22.33.235: icmp_seq=4 ttl=57 time=3.63 ms
--- e13678.dscb.akamaiedge.net ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3005ms
rtt min/avg/max/mdev = 3.425/7.923/12.455/4.396 ms