Doesn't send dhcpv6 request

[Jorge]

I'm using network-manager 1.22.10-1ubuntu2.1 in Ubuntu Focal 20.04. After a connection the internal dhcp doesn't send request to dhcpv6 server. All options in NM are default. IPv4 is ok.

Using tcpdump I can see the packages:

17:47:38.428145 IP6 fe80::426e:5cc5:ab6b:e126.546 > ff02::1:2.547: dhcp6 solicit
17:47:38.428902 IP6 fe80::20e:1eff:fe7a:9ed0.547 > fe80::426e:5cc5:ab6b:e126.546: dhcp6 advertise

After dhcp6 advertise the NM doesn't send any request. After some seconds I can see a timeout on logs.

NetworkManager[3803]: <warn> [1591735670.9313] dhcp6 (eno1): request timed out
NetworkManager[3803]: <info> [1591735670.9314] dhcp6 (eno1): state changed unknown -> timeout

As man says, we can change the dhcp client. If I change /etc/NetworkManager/NetworkManager.conf adding

[main]
dhcp=dhclient

so everything works nice.

I think there is some problem with the internal dhcp client of NetworkManager.

Tks

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.