Said It Here

VLAN interface missing after OS upgrade

Operating system updates can break system settings network panels entirely, preventing you from getting into networking. Additionally, configured VLAN interfaces like ens1.99 may disappear completely and no longer show up via ip addr or ip link.

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

  1. 1
    Manually flushing the parent interface config and restarting the networking service
  2. 2
    Removing the auto line for the vlan, removing the vlan_raw_device, and changing to a bridge config

In their words

Unedited, most upvoted first, each linked to the thread it came from.

During some testing it was noticed that the VLAN interface, ens1.99, was no longer shown via ip addr or ip link .source ↗

Chris Woelkers · Server Fault · 7 upvotes

we have two machines so far that now have broken system settings network panels. You can't get into networking.source ↗

perriwinkle_ · r/msp · 3 upvotes

Where this came up

People with this problem also raised