Creating VMs and LXC containers makes the host lose Internet connection

[ismokemysocks]

As the title states. I don't know why, but the PVE host loses connection to LAN and Internet... I have to physically go down to my home server, manually log in, kill the process and either wait a couple of minutes or reboot it (the latter one is not a must).

I've followed some of the steps (mainly the IOMMU stuff) that these two guys

1. https://yewtu.be/watch?v=xD9Xyt2mdSI
2. https://yewtu.be/watch?v=GoZaMgEgrHw

talk about. Other than that, the installation is fresh and clean.

Home server specs:

• Intel i5-10600K (I don't have a dedicated graphics card, so I'm using the integrated GPU)
• 32GB RAM
• 5x HDDs in RAIDZ

I'm new to Proxmox, so any help is greatly appreciated. Please let me know if you need anything and I'll be more that happy to provide it.

EDIT: forgot to mention that I tried spinning up an Alpine Linux container and this one did not make me lose LAN/Internet. However, it did not have any internet connectivity, so I suspect that it has something to do with bridging/networking etc.

EDIT 2: the other VM I've tried spinning up (multiple times, same result) is an Ubuntu VM, and the LXC container is a Debian container (template).

 

[Kingneutron]

To me, sounds like either IP address conflict or DNS.

Are you configuring your virtual stuff with DHCP? You need to make sure that the static IP address on vmbr0 is outside the DHCP address range from your router

 

[ismokemysocks]

@Kingneutron
Sorry for the dumb question, but at the beginning (ref. screenshot #1) I was prompted to set the IP address, the gateway, and the DNS. I changed the DNS from 1.1.1.1 to 127.0.0.1, the IP to 192.168.2.100/24 (which is what the server IP should and I want to be) and the gateway to 192.168.2.1.

Are you configuring your virtual stuff with DHCP?

I'm using my router as DHCP, if that's what you mean?

You need to make sure that the static IP address on vmbr0 is outside the DHCP address range from your router

I have changed vmbr0's IP from 192.168.2.100 to 192.168.2.200 (ref. screnshot #2) - is this what you mean? Or do I need to make adjustments anywhere else?

I guess what I want to do is:

• Have my home server's IP be 192.168.2.100.
• Be able to deploy VMs and containers on a different VLAN (192.168.5.xxx).

The vmbr0 can be on VLAN 2, too, no problem. But since I changed its final IP octet, I have to access the web UI through https://192.168.2.200:8006 instead of https://192.168.2.100:8006, so I've probably misconfigured something.

SCREENSHOT #1 (stock image)



SCREENSHOT #2

 

[ismokemysocks]

FWIW, I tried spinning up Proxmox in a VM on my desktop, downloaded Ubuntu 22.04 and created a VM and, here, everything seems to work fine? I'm at a loss... pity that it doesn't work, since I really wanted it to work on my home server.

Also, I've read that Proxmox does not issue refunds so I guess I'm not going to see the €100 I paid for the software

 

[leesteken]

If the router uses 192.168.122.1/24 (I'm assuming here), then the two subnets are separated and you need to configure routing between 192.168.122.0/24 and 192.168.100.0/24, which might be in different firewall zones depending on how you setup your router (and thus traffic might be blocked). Maybe start with a Proxmox management IP on the same subnet as the router and use the separate subnet for VM/CTs? Or maybe configure your router for 192.168.0.0/16?
There is a separate sub-forum about networking: https://forum.proxmox.com/forums/proxmox-ve-networking-and-firewall.17/

EDIT: Please note that Proxmox is completely free to run with all features enabled. Buying a support subscription is entirely optional (but much appreciated).

 

[ismokemysocks]

@leesteken Thank you for your reply. Both my desktop PC and my home server reside on the same VLAN (192.168.2.0) which is why I find this strange.

I could try to ask over in the networking section. Cheers.

 

[leesteken]

@leesteken Thank you for your reply. Both my desktop PC and my home server reside on the same VLAN (192.168.2.0) which is why I find this strange.

I agree that it is strange. Why do your other local systems sit in 192.168.2.0/24, while your router (and DNS) is 192.168.122.1 (and what is its netmask)? And why do you want Proxmox to use yet another local subnet 192.168.100.0/24?

 

[ismokemysocks]

@leesteken Oh, I now see why you got confused: no, picture #1 is a stock photo from the internet During installation I set the:

• CIDR to 192.168.2.100/24 (which was my home server IP to begin with).
• Gateway and DNS to 192.168.2.1