VNC into a qemu VM from LAN

I have a libvirt qemu vm (Win10) running on my nixos server. I want to access the vm from my lan via vnc.

How do I port forward on the nixos host so that I can connect from my lan onto the guest vm via vnc?

This is the network part of the vm:

<interface type='network'>
      <mac address='52:54:00:e1:ae:54'/>
      <source network='default'/>
      <model type='e1000e'/>
      <filterref filter='block_internet'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>

This is the default network:

  <forward mode='nat'/>
  <bridge name='virbr0' stp='on' delay='0'/>
  <mac address='52:54:00:27:57:81'/>
  <ip address='' netmask=''>
      <range start='' end=''/>
      <host mac='52:54:00:e1:ae:54' name='vm1' ip=''/>