Your server thinks that it has connectivity to the IPv6 Internet, but it doesn't. This isn't a Let's Encrypt issue specifically, it's just that your server needs to be able to talk to Let's Encrypt's servers in order to get a certificate (and probably to do other things).
You might be able to just remove the IPv6 configuration to have your system only try using IPv4, but it's be much better to see if you can fix your IPv6 routing so you can be on the current modern Internet.
Is it also possible to "nix" IPV6 and use IPV4 in the interim? Not the best solution, but it might work in a pinch? ...
then you can sort out IPV6 and get on the
I had a test with 2 servers in a different networks.
Not working update server had a same result like you, but good working update server in other network had a same result using the online tool https://unboundtest.com/.
so it'smay not this reason.
traceroute to 172.65.32.248 (172.65.32.248), 30 hops max, 60 byte packets
1 gateway (121.78.230.65) 1.926 ms 2.013 ms 2.008 ms
2 192.168.200.1 (192.168.200.1) 18.929 ms 19.072 ms 19.219 ms
3 203.246.170.101 (203.246.170.101) 0.626 ms 0.630 ms 0.680 ms
4 203.246.169.107 (203.246.169.107) 1.238 ms 203.246.169.150 (203.246.169.150) 0.915 ms 203.246.169.180 (203.246.169.180) 0.962 ms
5 * * *
6 218.145.42.206 (218.145.42.206) 17.440 ms * 16.812 ms
7 141.101.82.7 (141.101.82.7) 1.711 ms * *
8 218.145.42.206 (218.145.42.206) 16.228 ms 1.707 ms *
9 141.101.82.7 (141.101.82.7) 1.338 ms 1.303 ms 1.292 ms
10 * * *
11 * * *
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28 * * *
29 * * *
30 * * *
traceroute -T -p 443 172.65.32.0
traceroute to 172.65.32.0 (172.65.32.0), 30 hops max, 60 byte packets
1 gateway (121.78.230.65) 1.387 ms 1.525 ms 1.667 ms
2 192.168.200.1 (192.168.200.1) 0.955 ms 1.028 ms 1.208 ms
3 203.246.170.101 (203.246.170.101) 23.122 ms 23.121 ms 23.114 ms
4 203.246.169.137 (203.246.169.137) 0.967 ms 0.952 ms 203.246.169.120 (203.246.169.120) 20.414 ms
5 * * *
6 * * 218.145.42.206 (218.145.42.206) 34.885 ms
7 * * 141.101.82.7 (141.101.82.7) 1.051 ms
8 218.145.42.206 (218.145.42.206) 3.200 ms 3.161 ms 12.107 ms
9 * 141.101.82.7 (141.101.82.7) 1.569 ms *
10 * * *
11 * * *
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30 * * *
traceroute -T -p 443 172.65.0.0
traceroute to 172.65.0.0 (172.65.0.0), 30 hops max, 60 byte packets
1 gateway (121.78.230.65) 1.638 ms 1.776 ms 1.922 ms
2 192.168.200.1 (192.168.200.1) 0.976 ms 1.121 ms 1.297 ms
3 203.246.170.101 (203.246.170.101) 0.473 ms 0.474 ms 0.602 ms
4 203.246.169.137 (203.246.169.137) 0.925 ms 203.246.169.188 (203.246.169.188) 1.051 ms 203.246.169.107 (203.246.169.107) 0.899 ms
5 * * *
6 * * *
7 * 141.101.82.7 (141.101.82.7) 12.282 ms *
8 218.145.42.206 (218.145.42.206) 2.088 ms 2.001 ms 1.657 ms
9 141.101.82.7 (141.101.82.7) 11.955 ms 11.383 ms 11.345 ms
10 * * *
11 * * *
12 * * *
13 * * *
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30 * * *
traceroute -T -p 443 172.0.0.0
traceroute to 172.0.0.0 (172.0.0.0), 30 hops max, 60 byte packets
1 gateway (121.78.230.65) 2.034 ms 2.147 ms 2.143 ms
2 192.168.200.1 (192.168.200.1) 0.746 ms 0.862 ms 1.056 ms
3 203.246.170.101 (203.246.170.101) 16.200 ms 16.198 ms 16.191 ms
4 203.246.169.113 (203.246.169.113) 0.815 ms 203.246.169.144 (203.246.169.144) 0.865 ms 203.246.169.173 (203.246.169.173) 0.864 ms
5 203.246.163.106 (203.246.163.106) 0.977 ms 203.246.163.98 (203.246.163.98) 1.062 ms 203.246.163.106 (203.246.163.106) 0.969 ms
6 te0-2-1-2.ccr51.sel01.atlas.cogentco.com (154.18.20.1) 1.413 ms te0-2-0-2.ccr51.sel01.atlas.cogentco.com (154.18.20.33) 1.532 ms te0-2-1-2.ccr51.sel01.atlas.cogentco.com (154.18.20.1) 1.674 ms
7 be3010.ccr71.tyo01.atlas.cogentco.com (154.54.89.197) 30.896 ms 31.090 ms 31.060 ms
8 be3929.ccr72.tyo01.atlas.cogentco.com (154.54.83.190) 30.865 ms 30.842 ms 30.934 ms
9 be3696.ccr41.sjc03.atlas.cogentco.com (154.54.86.137) 136.901 ms 136.848 ms 138.471 ms
10 192.205.32.89 (192.205.32.89) 140.764 ms 140.709 ms 140.666 ms
11 * * *
12 * * *
13 * * *
14 * * *
15 * * *
16 32.130.18.59 (32.130.18.59) 193.023 ms 192.923 ms 193.602 ms
17 * * *
18 * * *
19 * * *
20 * * *
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29 * * *
30 * * *
traceroute -T -p 443 1.1.1.1
traceroute to 1.1.1.1 (1.1.1.1), 30 hops max, 60 byte packets
1 gateway (121.78.230.65) 1.669 ms 1.788 ms 1.999 ms
2 192.168.200.1 (192.168.200.1) 2.241 ms 2.421 ms 2.546 ms
3 203.246.170.101 (203.246.170.101) 0.683 ms 0.686 ms 0.682 ms
4 203.246.169.107 (203.246.169.107) 1.133 ms 203.246.169.137 (203.246.169.137) 1.110 ms 203.246.169.138 (203.246.169.138) 1.109 ms
5 121.78.30.70 (121.78.30.70) 1.684 ms 121.78.63.102 (121.78.63.102) 11.266 ms 121.78.30.70 (121.78.30.70) 1.998 ms
6 141.101.82.7 (141.101.82.7) 1.373 ms 141.101.82.9 (141.101.82.9) 1.621 ms *
7 one.one.one.one (1.1.1.1) 0.758 ms 0.836 ms 0.872 ms