Confirme que vc está usando o MTU ideal pra tua conexão.
tracepath -n 8.8.8.8
Se o IPv6 estiver ativo, desative-o.
Deu isso, mas eu não sei exatamente o que quer dizer:
...@...~$ tracepath -n 8.8.8.8
1?: [LOCALHOST] pmtu 1500
1: 192.168.1.1 1.877ms
1: 192.168.1.1 1.763ms
2: 192.168.1.1 3.151ms pmtu 1492
2: no reply
3: 187.100.40.145 7.492ms
4: 187.100.48.165 11.268ms asymm 5
5: 187.100.35.241 4.990ms
6: no reply
7: no reply
8: no reply
9: no reply
10: no reply
11: no reply
12: no reply
13: no reply
14: no reply
15: no reply
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18: no reply
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25: no reply
26: no reply
27: no reply
28: no reply
29: no reply
30: no reply
Too many hops: pmtu 1492
Resume: pmtu 1492