Review on TRENDnet 2.5Gase-T PCIe Network Adapter: High-Speed Ethernet Port, VLAN Tagging, Windows Support, Jumbo Frames - TEG-25GECTX by Jeff Diaz

Works well on Windows but other operating systems have trouble getting the correct speed profile to activate. Continued to show 1g instead of 2.5 on several different Linux distributions and Linux devices. Didn't show up on ESXI or Synology NAS. I know it's a new standard, but without the right hardware and driver support, devices are useless. I ended up finding some old 10GB NICs on Ebay and used them to increase my bandwidth. If/when the 2.5G/5G standard is built into motherboards and routers, then they will really come in handy.