Hi! I noticed that IPv6 fragments (even the short ones) are not passing from some remote (i.e. Frankfurt, London, US) networks back to me. Interestingly I can send fragments outside.
Here is an example (home host is connected over CATV DS-lite in Bülach), target is in a Frankfurt data center (traceroute goes apparently over Tinet and ZenLayer) but I observed the same behavior with many different targets across the globe:
[th@home ~]$ ip addr
...
20: enp6s0f4u1u4u4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 34:d0:b8:c0:b5:34 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.93/24 brd 192.168.1.255 scope global dynamic noprefixroute enp6s0f4u1u4u4
       valid_lft 77800sec preferred_lft 77800sec
    inet6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6/64 scope global dynamic noprefixroute 
       valid_lft 1209598sec preferred_lft 604798sec
    inet6 fe80::172:7df6:3d7:565b/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
       
[th@home ~]$ ping 2602:fb2b:110:1::a001 -s 1452
PING 2602:fb2b:110:1::a001 (2602:fb2b:110:1::a001) 1452 data bytes
1460 bytes from 2602:fb2b:110:1::a001: icmp_seq=1 ttl=54 time=21.0 ms
1460 bytes from 2602:fb2b:110:1::a001: icmp_seq=2 ttl=54 time=16.6 ms
1460 bytes from 2602:fb2b:110:1::a001: icmp_seq=3 ttl=54 time=16.8 ms
^C
--- 2602:fb2b:110:1::a001 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2001ms
rtt min/avg/max/mdev = 16.559/18.125/20.983/2.023 ms
[th@hroch ~]$ ping 2602:fb2b:110:1::a001 -s 1453
PING 2602:fb2b:110:1::a001 (2602:fb2b:110:1::a001) 1453 data bytes
^C
--- 2602:fb2b:110:1::a001 ping statistics ---
6 packets transmitted, 0 received, 100% packet loss, time 5130ms

root@home:/home/th# tcpdump -i enp6s0f4u1u4u4 -n host 2602:fb2b:110:1::a001 and port ! 22
dropped privs to tcpdump
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on enp6s0f4u1u4u4, link-type EN10MB (Ethernet), snapshot length 262144 bytes
12:13:49.521870 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: ICMP6, echo request, id 127, seq 1, length 1460
12:13:49.542825 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: ICMP6, echo reply, id 127, seq 1, length 1460
12:13:50.522269 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: ICMP6, echo request, id 127, seq 2, length 1460
12:13:50.538785 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: ICMP6, echo reply, id 127, seq 2, length 1460
12:13:51.523356 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: ICMP6, echo request, id 127, seq 3, length 1460
12:13:51.540131 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: ICMP6, echo reply, id 127, seq 3, length 1460
12:13:53.643286 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (0|1448) ICMP6, echo request, id 128, seq 1, length 1448
12:13:53.643310 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (1448|13)
12:13:54.676579 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (0|1448) ICMP6, echo request, id 128, seq 2, length 1448
12:13:54.676609 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (1448|13)
12:13:55.700630 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (0|1448) ICMP6, echo request, id 128, seq 3, length 1448
12:13:55.700658 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (1448|13)
12:13:56.724805 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (0|1448) ICMP6, echo request, id 128, seq 4, length 1448
12:13:56.724835 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (1448|13)
12:13:57.748646 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (0|1448) ICMP6, echo request, id 128, seq 5, length 1448
12:13:57.748677 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (1448|13)
12:13:58.772828 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (0|1448) ICMP6, echo request, id 128, seq 6, length 1448
12:13:58.772878 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (1448|13)
^C
18 packets captured
18 packets received by filter
0 packets dropped by kernel


root@fr1:/home/thlavacek# tcpdump -i enp6s19 -n host 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 and port ! 22
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on enp6s19, link-type EN10MB (Ethernet), snapshot length 262144 bytes
10:13:49.530779 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: ICMP6, echo request, id 127, seq 1, length 1460
10:13:49.530842 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: ICMP6, echo reply, id 127, seq 1, length 1460
10:13:50.528156 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: ICMP6, echo request, id 127, seq 2, length 1460
10:13:50.528214 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: ICMP6, echo reply, id 127, seq 2, length 1460
10:13:51.529777 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: ICMP6, echo request, id 127, seq 3, length 1460
10:13:51.529804 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: ICMP6, echo reply, id 127, seq 3, length 1460
10:13:53.653446 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (0|1448) ICMP6, echo request, id 128, seq 1, length 1448
10:13:53.656702 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (1448|13)
10:13:53.656739 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: frag (0|1448) ICMP6, echo reply, id 128, seq 1, length 1448
10:13:53.656748 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: frag (1448|13)
10:13:54.685428 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (0|1448) ICMP6, echo request, id 128, seq 2, length 1448
10:13:54.688970 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (1448|13)
10:13:54.689029 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: frag (0|1448) ICMP6, echo reply, id 128, seq 2, length 1448
10:13:54.689049 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: frag (1448|13)
10:13:55.709356 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (0|1448) ICMP6, echo request, id 128, seq 3, length 1448
10:13:55.713307 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (1448|13)
10:13:55.713337 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: frag (0|1448) ICMP6, echo reply, id 128, seq 3, length 1448
10:13:55.713346 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: frag (1448|13)
10:13:56.735380 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (0|1448) ICMP6, echo request, id 128, seq 4, length 1448
10:13:56.738622 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (1448|13)
10:13:56.738682 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: frag (0|1448) ICMP6, echo reply, id 128, seq 4, length 1448
10:13:56.738699 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: frag (1448|13)
10:13:57.757374 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (0|1448) ICMP6, echo request, id 128, seq 5, length 1448
10:13:57.762591 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (1448|13)
10:13:57.762651 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: frag (0|1448) ICMP6, echo reply, id 128, seq 5, length 1448
10:13:57.762671 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: frag (1448|13)
10:13:58.779440 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (0|1448) ICMP6, echo request, id 128, seq 6, length 1448
10:13:58.782589 IP6 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 > 2602:fb2b:110:1::a001: frag (1448|13)
10:13:58.782620 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: frag (0|1448) ICMP6, echo reply, id 128, seq 6, length 1448
10:13:58.782628 IP6 2602:fb2b:110:1::a001 > 2a02:aa11:380:300:8039:5fbc:b93a:bbc6: frag (1448|13)
^C
30 packets captured
30 packets received by filter
0 packets dropped by kernel

[th@home ~]$ traceroute 2602:fb2b:110:1::a001
traceroute to 2602:fb2b:110:1::a001 (2602:fb2b:110:1::a001), 30 hops max, 80 byte packets
 1  2a02:aa11:380:300::1 (2a02:aa11:380:300::1)  0.936 ms  1.116 ms  1.244 ms
 2  2a02:aa04:0:1030::1 (2a02:aa04:0:1030::1)  12.881 ms  23.713 ms  23.720 ms
 3  cargos101-bundle-ether1119-1301.v6.aorta.net (2a02:aa00:1:302::1)  19.879 ms  21.590 ms  23.424 ms
 4  * * *
 5  * * *
 6  2001:1700:100::1 (2001:1700:100::1)  23.372 ms  16.299 ms *
 7  * * *
 8  2001:668:0:2:ffff:0:d5c8:74e1 (2001:668:0:2:ffff:0:d5c8:74e1)  29.327 ms  27.781 ms  29.250 ms
 9  2001:668:0:3:ffff:1:0:1ce (2001:668:0:3:ffff:1:0:1ce)  26.357 ms  26.205 ms  27.720 ms
10  2a0b:21c0:1001:14f::2 (2a0b:21c0:1001:14f::2)  35.534 ms 2a0b:21c0:1001:150::2 (2a0b:21c0:1001:150::2)  37.116 ms 2a0b:21c0:1001:14f::2 (2a0b:21c0:1001:14f::2)  37.053 ms
11  2a0b:21c0:1002:15::6 (2a0b:21c0:1002:15::6)  32.455 ms  32.487 ms 2a0b:21c0:1002:15::2 (2a0b:21c0:1002:15::2)  26.470 ms
12  2602:fb2b:110:1::a001 (2602:fb2b:110:1::a001)  22.579 ms  23.979 ms  27.289 ms

root@fr1:/home/thlavacek# traceroute 2a02:aa11:380:300:8039:5fbc:b93a:bbc6
traceroute to 2a02:aa11:380:300:8039:5fbc:b93a:bbc6 (2a02:aa11:380:300:8039:5fbc:b93a:bbc6), 30 hops max, 80 byte packets
 1  2602:fb2b:110:1::1001 (2602:fb2b:110:1::1001)  0.711 ms  0.566 ms  0.658 ms
 2  2a0b:21c0:1002:15::1 (2a0b:21c0:1002:15::1)  10.797 ms  10.964 ms  11.289 ms
 3  2a0b:21c0:1001:15c::1 (2a0b:21c0:1001:15c::1)  1.575 ms 2a0b:21c0:1001:14f::1 (2a0b:21c0:1001:14f::1)  0.386 ms  0.356 ms
 4  2404:ff40:1:151::1 (2404:ff40:1:151::1)  0.242 ms 2a0b:21c0:1001:166::1 (2a0b:21c0:1001:166::1)  0.475 ms 2404:ff40:1:151::1 (2404:ff40:1:151::1)  0.205 ms
 5  2404:ff40:1:3c::1 (2404:ff40:1:3c::1)  0.378 ms 2404:ff40:1:3d::1 (2404:ff40:1:3d::1)  0.539 ms 2404:ff40:1:3b::1 (2404:ff40:1:3b::1)  0.416 ms
 6  2404:ff40:1:38::2 (2404:ff40:1:38::2)  0.534 ms 2404:ff40:1:37::2 (2404:ff40:1:37::2)  0.640 ms  0.609 ms
 7  de-fra11b-ri1-ae58-0.v6.aorta.net (2001:730:2d04:a::d52e:b001)  0.549 ms  0.637 ms  0.628 ms
 8  de-fra11b-rc1-lo0-0.v6.aorta.net (2001:730:2d00::5474:80d4)  9.637 ms  9.592 ms  9.563 ms
 9  ch-zrh03a-rc2-lo0-0.v6.aorta.net (2001:730:2c00::5474:801d)  9.688 ms  9.587 ms  9.417 ms
10  * * *
11  cargos101-lo1.v6.aorta.net (2001:730:2700::5474:faa0)  9.679 ms  9.825 ms  9.883 ms
12  2a02:aa00:1:302::2 (2a02:aa00:1:302::2)  13.789 ms  13.794 ms  13.727 ms
13  2a02:aa04:0:1030:1c61:2328:474b:def7 (2a02:aa04:0:1030:1c61:2328:474b:def7)  20.507 ms  28.361 ms  23.327 ms
14  2a02:aa11:380:300:8039:5fbc:b93a:bbc6 (2a02:aa11:380:300:8039:5fbc:b93a:bbc6)  28.261 ms  28.236 ms  23.050 ms