Why do you need VirIO driver?
It's useful when you use Linux/Windows VMs in PVE.
Usually when you attach a network to the VM, you would click the "Hardware" -> "Network Device" -> "Bridge" -> "vmbr0" or "vmbr1" -> Choose Model: VirtIO (paravirtualized)
vmbr0 or vmbr1 is the network bridge you created in the PVE and it will bridge the VM with the router which your PVE connected with.
After you boot the VM, try to download the latest VirtIO drivers for Linux or Windows. More info can be found here: https://pve.proxmox.com/wiki/Windows_VirtIO_Drivers
For enabling virtio drivers on Linux, here's the info : https://www.linuxquestions.org/questions/debian-26/%5Bsolved%5D-how-do-i-use-virtio-drivers-in-debian-in-a-kvm-virtual-machine-4175442186/
In short
add lines in file /etc/initramfs-tools/modules
virtio_pci
virtio_blk
virtio_net
then do the command
sudo update-initramfs -u
then reboot to check speed of IO
check whether virtio module is loaded:
dmesg | grep -i virtio
What can VirtIO drivers give you?
For faster ethernet. Mode VirtIO (paravirtualized) can bring up 10Gbps network speed.
The default Mode Intel e1000 can work fine on Linux and Windows at 1Gbps which is slow.
Tips
1) For selecting the default network adapter on Windows, please read here: https://services.northwestern.edu/TDClient/30/Portal/KB/ArticleDet?ID=1563
Also here's a video:
How to Change Network Priority of Connection on Windows 10
https://www.youtube.com/watch?v=ig6gtgIW6As
E.g. Windows can choose adapter #2 as default while adapter #1 will be used only if #2 is down.