Checkout PFSense and PFBlocker-NG. It's a geofence blocker to DENY all incomming requests from various IP subnets that you select on the public side. If you have any open ports (say for games or otherwise on your home network) this will really cut back on system load/login attempts. It can just drop the packets entirely, not even entertaining them.
You'd ideally want to use a VPN and not expose any other ports on the firewall. For example never open an SSH port. If you do use a keypair and make it a non-standard port. But having a VPN would prevent you from even needing to open SSH ports as the VPN would essentially put you on the LAN. Most consumer routers will let you setup a VPN server for your LAN now.
But something like hosting a webserver at home this (Geoblocking) can really help with. In addition to using cloudflare as your domain registrar for DDOS protection.
Here's a video on it:
https://www.youtube.com/watch?v=oNo77CMoxUM
If you have a consumer firewall you may or may not have access to doing this. (Geoblocking)
With pihole you could create lists of domains (say from certain countries) that you do not want to resolve for name resolution. But it would not stop those countries from attempting to access open ports on your network. I.e. ingress vs egress
By default your home firewall/router, if it is a consumer model, should not have any ports open.
Hope this helps!
I have the exact same server. The drive caddies are hit and miss on ebay. Bought a few, didn't fit. Gave up on buying any. I see you pulled out the place holder bays out. I used a 3d printer and printed some of the drive caddies off of thingiverse. You'll want to search your exact model. But still ended up snipping some off so they would slide in.
The server has an option to put a PCIE riser nearest to your power supply there. There's a few of those on ebay as well. Looks like you have one installed on the opposite side next to the SATA cables plugged in. That would let you swap that network card you have in there for a GPU and power it if you wanted.
Seeing as you have RAM in both sides of the motherboard I would wager this is a DUAL CPU system.
Might search for the manual of your exact model/make so you can see what all features and hardware it can use. Get your ILO setup too.
Grats on the system! Mine sits around 200-300 watts with minimal load.