i observe that the v4 vrrp virtual interface on the troublesome router has an extra ipv6 address, 2001:418:8006:0:349e:1bc5:a7e8:844d/64, in the real global space 9: vrrp4-2-6@eno1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state LOWERLAYERDOWN group default qlen 1000 link/ether 00:00:5e:00:01:06 brd ff:ff:ff:ff:ff:ff protodown on inet 198.180.150.126/25 metric 1024 scope global vrrp4-2-6 valid_lft forever preferred_lft forever -> inet6 2001:418:8006:0:349e:1bc5:a7e8:844d/64 scope global dynamic mngtmpaddr stable-privacy valid_lft 2588868sec preferred_lft 601668sec inet6 fe80::a502:68e5:2c20:cadb/64 scope link stable-privacy valid_lft forever preferred_lft forever 10: vrrp6-2-6@eno1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state LOWERLAYERDOWN group default qlen 1000 link/ether 00:00:5e:00:02:06 brd ff:ff:ff:ff:ff:ff protodown on protodown_reason <7> inet6 2001:418:8006::126/64 metric 1024 scope global valid_lft forever preferred_lft forever inet6 fe80::77f2:a95d:8e32:730a/64 scope link stable-privacy valid_lft forever preferred_lft forever while the untroubled router does not 6: vrrp4-4-6@eno3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000 link/ether 00:00:5e:00:01:06 brd ff:ff:ff:ff:ff:ff inet 198.180.150.126/25 metric 1024 scope global vrrp4-4-6 valid_lft forever preferred_lft forever inet6 fe80::9e58:24dc:52b6:1ce9/64 scope link stable-privacy valid_lft forever preferred_lft forever 7: vrrp6-4-6@eno3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000 link/ether 00:00:5e:00:02:06 brd ff:ff:ff:ff:ff:ff inet6 2001:418:8006::126/64 metric 1024 scope global valid_lft forever preferred_lft forever inet6 fe80::9b66:4468:512:fc74/64 scope link stable-privacy valid_lft forever preferred_lft forever