Hosting guests Virtual Machine on Cachyos Internet connectivity

Issues & Assistance
1

Hi all, ive been using cacyos with no issues for the last 2 weeks. everything works well. However the qemu vm installs guests well but lacks internet conection. i am using core ultra 125u, ram 32GB 5600,

I was advised from the arch forum to use vmware which i did and it has internet but again the problem is the screen tearing, i disabled the 3D settings on the display options but that left me with minor screen flikering on the guest session.

i still prefer qemu/kvm through virtual machine manager but now no internet. tried lots of work arrounds including uninstall and installs, , fire wall disabling aswell as cachy hello options but nothing with internet con nectivity. this works in other kde versions wonder why not here.

2

Perhaps share your network selection.

I have no net issues In any of my KVM installs..

<interface type="direct">
  <mac address="52:54:00:72:ef:b0"/>
  <source dev="eth0" mode="bridge"/>
  <target dev="macvtap1"/>
  <model type="virtio"/>
  <alias name="net0"/>
  <address type="pci" domain="0x0000" bus="0x01" slot="0x00" function="0x0"/>
</interface>

BTW Welcome to our forum @Nero_Rozz

3

Network source: ‘default’ NAT
Device model: virtio

You need libvirt and VirtIO Drivers for Windows Guests.
There are some instructions on the Internet.

4

I have the same problem, and sometimes disabling the firewall worked but sometimes not. Then I tried creating a QEMU/KVM User session as pictured in the screenshot and the internet works 100% all the time in the guest.

Screenshot_20250823_124636
Screenshot_20250823_124636563×575 30.8 KB

5

I was so ready to lay out everything I did to try to get my internet working on a VM, and it turns out after studying nftables, iptables, bridge devices, all I needed to do was to switch to a QEMU/KVM User Session.

Thanks, JB

6

Just bumping this to also say thanks re: the User Session suggestion. I freely admit I don’t know WTF I’m doing. I have used QEMU/KVM with success on other distros. On Fedora I just use dnf install @virtualization and haven’t had issues. For whatever reason, no Internet on CachyOS but switching to a User Session worked, and that’s A-OK w/ me. Whatever works for the few job related Windows apps I need. Thanks @JBTR

7

Just wanted to tag in here as well… I was really baffled about WTF was going on with the guest networking. I’ve used virt-manager on Debian, Mint, Fedora, etc. etc. Never had to use ‘user session’ before. But it worked this time, here, on cachyos.

8

Hi there, new CachyOS user here and I encountered this no network issue as well after following the setup here:

For me the fix was to add the following line to /etc/libvirt/network.conf:

firewall_backend = "iptables"

then restart libvirtd:

sudo systemctl restart libvirtd

I’m able to run it without the “User Session”

UPDATE: Thanks to this thread I looked into user sessions a little more, and decided it’s actually the way to go for my purpose since it provides better host network isolation, which is something I’d rather have:

9

bro thank you so much, I spent an hour searching for an error before I found this post.

Still curious why this happens though. I didn’t have the Issue on Manjaro.
And nftables actually contains a section which respects lilbvirt.