Host a middle node
Keep in mind that none of the hardware you listed is great for hosting. It could work but I would go for somethinga little more modern. Something like a i5-7500 would be great. Get a router with vlans since you probably will want to segment the network.
For networking make sure you have a solid low latency reasonable bandwidth connection. I would do gigabit fiber since that will provide a decent amount of bandwidth while having low latency.
Also you could look into running a i2p node on the same machine since they both need volunteers.