Transcoding on truenas doesn't work

[Artik1]

Your setup actually looks really good too for my needs, but it's way out of budget.
My current setup is an HP 250 G6:

• i3-6006u
  
• 8Gb ddr4
  
• 1,6TB of random HDDs connected to the USB ports (yikes 😬)
  
• Gigabit Ethernet
  

It currently is

• A Truenas scale server
  
• A jellyfin server - Struggling with transcoding
  
• A basic smb Nas
  
• A Minecraft server for me and my family (max 10 people at once on a plain paper vanilla world, but planning on using some modpacks in the future after the upgrade) - Struggling with anything
  
• A navidrome server
  
• An immich server
  

I'd like to be able to to everything I'm currently doing as well as self hosting Mediacms, DisqueTV, paperless ngx and Stirling PDF

My budget is 200€ at most, disks excluded.
I've seen many HP ProDesks 600 and 800 series; Lenovo p520s and lastly dell optiplexes, but they are often too expensive or very old

What do you suggest?