# Network errors with Hyper-V Switch based on Mellanox Connectx-3



## tony95 (Jan 26, 2021)

I have two TrueNAS servers, one is on Windows 10 and another is on Server 2019, both running in Hyper-V.  I am having a similar issue on both systems.  TrueNAS runs on FreeBSD 12.2.  I have narrowed it down to a networking issue inside of the VM.  The issue doesn't occur anywhere else on my network or in a Win10 guest VM on same system and it is not a problem with the disk drives because it occurs writing to a single SSD as well as a Z2 array. Both systems are using a virtual switch based on Mellanox Connectx-3 10G adapters.

What is happening is that everything boots up and runs fine, but I will get random network errors. Every so often, 5-30 minutes, I get "an unexpected network error has occurred" in Beyond Compare and/or qBittorrent when I am writing to the TrueNAS server. One file will error and then it will continue with the rest of the copy and I just have to resend that one file. I can copy several Terabytes and maybe a handful of files will fail or in qBittorrent a few downloads will error every 5-30 minutes usually resulting in all the downloads failing several times.

I have tried # sysctl net.link.ether.inet.max_age=60 but didn't seem to help.  I am wired in with 10G fiber.  I have tried disabling VMQ and also Enable MAC address spoofing in Hyper-V, but didn't make a difference that I can tell. Any idea what the problem is, I would really like to be able to use this server reliably. Please help


----------



## SirDice (Jan 26, 2021)

GhostBSD, pfSense, TrueNAS, and all other FreeBSD Derivatives


----------



## tony95 (Jan 26, 2021)

I saw that, however they have already said they don't recommend Hyper-V, I have an issue open there but so far no response.  If it is an underlying issue with FreeBSD 12.2 then maybe someone has an idea how to troubleshoot?


----------



## tony95 (Jan 27, 2021)

So, this happens a lot more frequently when the host is under heavy load.  I have 32GB memory coming from slowegg, it may be a resource issue.  I have 16GB total with 8GB dedicated to FreeBSD.  I would think 8GB for host would be enough.


----------



## tony95 (Jan 28, 2021)

I changed the NIC in the Virtual Switch from Mellanox Connectx-3 to the built-in RealTek Gigabit adapter and problem persists. I also upgraded the ram to 32GB and set the CPU reserve to 100%, still same issue.


----------



## tony95 (Feb 1, 2021)

I installed onto bare metal and same problem


----------

