Just discovered on a site for the sale of used equipment. Someone added an additionnal nic to the location of the VGA connector.
So he bought this :
https://www.aliexpress.com/item/1005004616272749.html
and connected it to the mini pcie connector inside.
Btw you can find a 2.5Gbps Nic for cheaper here :
and this is the result :
So if you have an old optiplex 3050, maybe you can give it a new life 
Very cool. I've seen another mod where someone created their own m.2 to PCI and added a 4 port card into their usff machine!
I'd like to do this mod but not sure I'd have the confidence to create my own port!
You can do the same with a Lenovo M720q - Lenovo M720Q Tiny Build Documentation and Guide, without any DIY mods.
Or get a Cyberoam CR/15/25/35/(W)ING, for $25 and up, unless you need the excessive CPU power.
While you might get lucky, you're betting on the mainboard power delivery and cooling system to cope with a that additional load. 1 (additional-) port, yes - 2, maybe (probably), 4 has seen other boards (futro) crumble and crash - even more so if you go beyond 1000BASE-T, don't get too greedy (unless you're willing to risk defeat and hardware damage).
Don't get me wrong, it might work out well - but doesn't need to, so be aware of the risks and how far you can go without doing Russian Roulette.
