Ubuntu Bionic (which contained v0.97 and v0.98) are out of standard support, and I cannot reproduce this issue on Ubuntu Focal (Netplan v0.104) anymore. So I'm closing this bug report.
Please re-open if you think this is still an issue. root@ff:~# cat /etc/netplan/tunnels-lp1812680.yaml network: version: 2 renderer: networkd tunnels: tun0: mode: gre local: 1.1.1.1 remote: 2.2.2.2 addresses: - 10.7.10.50/30 tun1: mode: gre local: 3.3.3.3 remote: 4.4.4.4 addresses: - 10.7.10.54/30 root@ff:~# netplan apply root@ff:~# cat /run/systemd/network/10-netplan-tun0* [NetDev] Name=tun0 Kind=gre [Tunnel] Independent=true Local=1.1.1.1 Remote=2.2.2.2 [Match] Name=tun0 [Network] LinkLocalAddressing=ipv6 Address=10.7.10.50/30 ConfigureWithoutCarrier=yes root@ff:~# 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 valid_lft forever preferred_lft forever 2: gre0@NONE: <NOARP> mtu 1476 qdisc noop state DOWN group default qlen 1000 link/gre 0.0.0.0 brd 0.0.0.0 3: gretap0@NONE: <BROADCAST,MULTICAST> mtu 1462 qdisc noop state DOWN group default qlen 1000 link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff 4: erspan0@NONE: <BROADCAST,MULTICAST> mtu 1450 qdisc noop state DOWN group default qlen 1000 link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff 5: tun0@NONE: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN group default qlen 1000 link/gre 1.1.1.1 peer 2.2.2.2 inet 10.7.10.50/30 brd 10.7.10.51 scope global tun0 valid_lft forever preferred_lft forever 6: tun1@NONE: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN group default qlen 1000 link/gre 3.3.3.3 peer 4.4.4.4 inet 10.7.10.54/30 brd 10.7.10.55 scope global tun1 valid_lft forever preferred_lft forever 586: eth0@if587: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000 link/ether 00:16:3e:67:65:fb brd ff:ff:ff:ff:ff:ff link-netnsid 0 inet 10.238.94.77/24 metric 100 brd 10.238.94.255 scope global dynamic eth0 valid_lft 3598sec preferred_lft 3598sec inet6 fd42:7213:f20e:bd74:216:3eff:fe67:65fb/64 scope global tentative mngtmpaddr noprefixroute valid_lft forever preferred_lft forever inet6 fe80::216:3eff:fe67:65fb/64 scope link valid_lft forever preferred_lft forever => Tunnels end up in "UP,LOWER_UP" state ** Changed in: netplan.io (Ubuntu) Status: Confirmed => Won't Fix ** No longer affects: netplan -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1812680 Title: gre tunnels are down after netplan apply To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/netplan.io/+bug/1812680/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs