I'm running a Windows Server 2022 host with 16 CPU cores and 128GB of RAM, strictly using it for Hyper-V. So far, I've set up 9 VMs, primarily Ubuntu (22.04 and 24.04 LTS) and a few Windows Server 2022 instances, and they've been running smoothly. However, when I attempted to add a 10th VM (another Ubuntu instance), I encountered some strange networking problems. The VM's Internet connectivity on the IT network is inconsistent, often coming through in bursts with long pauses. I also can't access this new VM from the IT network as I could with the others.
I deleted and recreated the VM, but the same issues persisted. Even after using a completely new 24.04 Ubuntu image, I faced installation failures during the kernel step when all prior installations went without a hitch. I've messed around with the NICs too, deleting and re-adding them, but that didn't help either. All my previous VMs are functioning perfectly, but it's like something's broken after adding the 9th VM. Although I've allocated my 16 CPU cores among all VMs, I feel like I'm not overloading it too badly. Any thoughts on what might be causing these issues?
5 Answers
Could it be an IP conflict? Sometimes, network hiccups happen due to IP issues. Have you ensured all your VMs have unique static IPs?
Gotcha. Sounds frustrating! It might not be an IP issue then.
Just a couple of questions for clarification:
- Are any of the VMs clones, or were they all built from scratch?
- Are you using paravirtualized kernels for any of the Linux VMs? Sometimes certain kernels have known issues.
- Also, what's the RAM utilization looking like?
No clones here, all VMs were set up manually with full kernels. RAM usage is about 68%, and I have around 36 vCPUs assigned across all VMs.
What’s your storage situation? In the past, some hypervisors had caps on storage over-provisioning. Check if your storage allocation is healthy!
I have plenty of space left—approximately 700GB used out of 1.7TB.
First off, double-check that your power profile on the Hyper-V host is set to high performance. That might help with stability and performance.
What's your networking setup like? Are you using NAT? Do you have an external switch hooked up? Also, can you access the VMs from the Host? Sometimes, a local firewall might mess with the traffic too.
On my Windows 11 setup with around 10-12 VMs, I don't face similar issues with mixed Windows and Linux VMs, so it shouldn’t be too complicated.
I did think about that, but luckily, all my IPs are static and assigned correctly. Network connectivity is working, but it's just super erratic.