Hyper-V - Ubuntu 20 LTS no network connections

Problem: Created a new Ubuntu 20 LTS VM in Hyper-V, but the installer found no network.

Specs:

Type: Generation 1
8 GB RAM (dynamic)
Default storage
4 vCPUs
Stock Ubuntu Server 20.04 LTS ISO

Observation:

No matter what I tried — ensuring Default Network Adapter settings were set to External, or creating a Legacy Network adapter — nothing made a connection inside the VM.

Solution:

I re-rolled it.

Deleted the Gen 1 VM and created a Gen 2 VM instead.
Had to turn off Secure Boot in Settings for it to boot at all. This is a test VM, so security was not a consideration — plan accordingly.

Hyper-V Generation 2 settings screenshot

Extras:

Enhanced session with linux-vm-tools: https://github.com/Microsoft/linux-vm-tools/wiki/Onboarding:-Ubuntu