No egress connectivity cannot from a guest VM when its primary interface is attached to a primary UserDefinedNetwork.

4.17.0-rc.2 (and was also observed on 4.17.0-rc.6)
CNV 4.17.0 (brew.registry.redhat.io/rh-osbs/iib:810627, and was also observed on brew.registry.redhat.io/rh-osbs/iib:822926)

100%

1.
On a clutser with CNV and UDN enabled (I had to enable the TechPreviewNoUpgrade feature-set, and the primaryUserDefinedNetworkBinding and deployKubevirtIpamController feature-gates in HCO).

2.
Create the namespace yoss-ns:
$ oc create ns yoss-ns

3Apply a UDN resource like this one:
apiVersion: k8s.ovn.org/v1
kind: UserDefinedNetwork
metadata:
  name: primary-l2-net
  namesapce: yoss-ns
spec: 
  topology: Layer2
  layer2:
      role: Primary
      subnets: [10.10.0.0/24]
  ipamLifecycle: Persistent

(Note that it has the `ipamLifecycle: Persistent` set).

4.
Create a VM using the attached vm-a.yaml, with the primary interface attached to the UDN.

5.
Start the VM:
virtctl start vm-a

6.
Once the VM is running and completes its startup - access its console and check the IP address of its primary interface:
$ virtctl console vm-a
uccessfully connected to vm-a console. The escape sequence is ^]

vm-a login: fedora
Password: 
Last failed login: Mon Sep 30 14:07:34 UTC 2024 on ttyS0
There was 1 failed login attempt since the last successful login.
Last login: Mon Sep 30 07:55:10 on ttyS0

7.
Try pinging 8.8.8.8
[fedora@vm-a ~]$ ping 8.8.8.8 -w 5
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.

--- 8.8.8.8 ping statistics ---
5 packets transmitted, 0 received, 100% packet loss, time 4130ms

No response

Successful egress connectivity