Thanks for the response. Here is the output, along with the command echoed by 'set -x' in Bash:

+ export LANG=C + LANG=C + ip a 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host noprefixroute valid_lft forever preferred_lft forever 2: enp0s13f0u3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000 link/ether d0:c0:bf:4e:30:1a brd ff:ff:ff:ff:ff:ff inet 192.168.1.252/24 brd 192.168.1.255 scope global noprefixroute enp0s13f0u3 valid_lft forever preferred_lft forever inet6 2a02:1810:9514:8d00::6fcb/128 scope global dynamic noprefixroute valid_lft 215843sec preferred_lft 52433sec inet6 fe80::b78:f559:3ba2:30a7/64 scope link noprefixroute valid_lft forever preferred_lft forever 3: wlan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000 link/ether c6:05:00:75:d2:91 brd ff:ff:ff:ff:ff:ff permaddr 2c:6d:c1:92:a8:e7 + getent ahostsv6 google.com 2a00:1450:400e:803::200e STREAM google.com 2a00:1450:400e:803::200e DGRAM 2a00:1450:400e:803::200e RAW + ping -c1 -6 google.com ping: connect: Network is unreachable + dig google.com ; <<>> DiG 9.18.18 <<>> google.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 8148 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 65494 ;; QUESTION SECTION: ;google.com. IN A ;; ANSWER SECTION: google.com. 241 IN A 142.250.179.206 ;; Query time: 3 msec ;; SERVER: 127.0.0.53#53(127.0.0.53) (UDP) ;; WHEN: Sat Sep 16 10:53:16 CEST 2023 ;; MSG SIZE rcvd: 55 + dig -t AAAA google.com ; <<>> DiG 9.18.18 <<>> -t AAAA google.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6630 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 65494 ;; QUESTION SECTION: ;google.com. IN AAAA ;; ANSWER SECTION: google.com. 102 IN AAAA 2a00:1450:400e:803::200e ;; Query time: 0 msec ;; SERVER: 127.0.0.53#53(127.0.0.53) (UDP) ;; WHEN: Sat Sep 16 10:53:16 CEST 2023 ;; MSG SIZE rcvd: 67 + dig @8.8.8.8 -t AAAA google.com ; <<>> DiG 9.18.18 <<>> @8.8.8.8 -t AAAA google.com ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 28372 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 512 ;; QUESTION SECTION: ;google.com. IN AAAA ;; ANSWER SECTION: google.com. 75 IN AAAA 2a00:1450:400e:802::200e ;; Query time: 23 msec ;; SERVER: 8.8.8.8#53(8.8.8.8) (UDP) ;; WHEN: Sat Sep 16 10:53:16 CEST 2023 ;; MSG SIZE rcvd: 67 + dig @2001:4860:4860::8888 -t AAAA google.com ;; UDP setup with 2001:4860:4860::8888#53(2001:4860:4860::8888) for google.com failed: network unreachable. ;; UDP setup with 2001:4860:4860::8888#53(2001:4860:4860::8888) for google.com failed: network unreachable. ;; UDP setup with 2001:4860:4860::8888#53(2001:4860:4860::8888) for google.com failed: network unreachable. + drill google.com ;; ->>HEADER<<- opcode: QUERY, rcode: NOERROR, id: 10255 ;; flags: qr rd ra ; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;; google.com. IN A ;; ANSWER SECTION: google.com. 241 IN A 142.250.179.206 ;; AUTHORITY SECTION: ;; ADDITIONAL SECTION: ;; Query time: 0 msec ;; SERVER: 127.0.0.53 ;; WHEN: Sat Sep 16 10:53:16 2023 ;; MSG SIZE rcvd: 44 + drill -t AAAA google.com ;; ->>HEADER<<- opcode: QUERY, rcode: NOERROR, id: 7219 ;; flags: qr rd ra ; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;; google.com. IN AAAA ;; ANSWER SECTION: google.com. 102 IN AAAA 2a00:1450:400e:803::200e ;; AUTHORITY SECTION: ;; ADDITIONAL SECTION: ;; Query time: 0 msec ;; SERVER: 127.0.0.53 ;; WHEN: Sat Sep 16 10:53:16 2023 ;; MSG SIZE rcvd: 56 + drill @8.8.8.8 -t AAAA google.com ;; ->>HEADER<<- opcode: QUERY, rcode: NOERROR, id: 62322 ;; flags: qr rd ra ; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;; google.com. IN AAAA ;; ANSWER SECTION: google.com. 282 IN AAAA 2a00:1450:400e:802::200e ;; AUTHORITY SECTION: ;; ADDITIONAL SECTION: ;; Query time: 38 msec ;; SERVER: 8.8.8.8 ;; WHEN: Sat Sep 16 10:53:16 2023 ;; MSG SIZE rcvd: 56 + drill @2001:4860:4860::8888 -t AAAA google.com Error: error sending query: General LDNS error

Furthermore, to answer -thc's questions: 'ip a' seems to show both types of IPv6 addresses, global and local (see above).

'ip -6 route' shows both routes for the global and local address:

2a02:1810:9514:8d00::6fcb dev enp0s13f0u3 proto kernel metric 100 pref medium fe80::/64 dev enp0s13f0u3 proto kernel metric 1024 pref medium

And, if I understood the question of pinging with scope correctly, I should try pinging the IPv6 local address of the router, but it doesn't seem to be shown directly - the first address is my own global IPv6 address and the second one the subnet of the link-local address.

I tried doing a traceroute6 from the working device to get the IPv6 address of the router (first hop), and whilst pinging that from that device works, it also yields 'Network is unreachable' from my misbehaving Arch box. Probably expectedly, trying to ping another IPv6 device in my local network that is directly connected to the same gateway also yields 'Network is unreachable' (this is the Debian device on which IPv6 works fine).