FreeNAS 11.2 U5 Stability issues

[hybrid]

Hi,
I recently built a FreeNAS,~6 months ago. I use only NFS/SMB, no jails, no plugins, no iSCSI....
My problem is that the system crash every 15 days to 1-2 months. The computer is still on, but it's like if there is no network connection.
To be honest I didn't see anything in the logs when I looked ~2 months ago.

Here are the specs :

• Gigabyte Aorus B450M
• AMD Ryzen 7 2700X
• 32 GB RAM (@2400Mhz)
• 4x10TB in raidz1 for storage, 250 GB SSD to boot
• Mellanox 10 GB SFP+ networking card (I don't have the exact model but I can get it if it's really needed)
  

I can give as much informations as needed to make it work, my current problem is that I don't really know where to look... :(
Looking for ideas/solutions :)
Thanks