Using a second NIC to share access to router in both directions, but also lost GUI LAN access

[DR4GON]

I have an Asus Z8NA-D6C running Proxmox. It has dual 10Gbe. I have a second computer running Ubuntu 20.04. It has a single 10GBe. I have a 10GBe switch in another room, connected to multiple devices including the router.

My current setup is such that I only have one 10GBe port in the room the server and computer are in. I would like to have 10GBe come into the room, via Proxmox, and then use Proxmox to forward 10GBe to the computer. The plan is to then have Ubuntu programs assessed by a computer connected to the router.

I know how to share NIC's in GUI Ubuntu 20.04, and I used to use a VM on Proxmox to share the network. However, I would like to know if there is a way to do it with Proxmox itself via CLI. It will make a future setup possible if it can be done without using a VM to accomplish, but if I have to use a VM, something less needy than a full GUI Ubuntu would be ideal.

IP's:
Proxmox 192.168.0.1
Ubuntu 192.168.0.2
Router 192.168.0.10
Other computers 192.168.0.*

So far I have looked at nano /etc/network/interfaces but don't know what I'm looking at other that which NIC is which.

auto lo
iface lo inet loopback

#This is incoming NIC
iface enp2s0 inet manual

#This is outgoing NIC
iface enp3s0 inet manual   

auto vmbr0
iface vmbr0 inet static
    address 192.168.0.1/24
    gateway 192.168.0.10
    bridge-ports enp2s0
    bridge-stp off
    bridge-fd 0

auto vmbr1
iface vmbr1 inet static
    address 192.168.0.2/24
    bridge-ports enp3s0
    bridge-stp off
    bridge-fd 0

I have looked at Proxmox GUI, but there isn't a clear method to share a NIC, and now I can't even access Proxmox at all.

Results of ip a is

1: lo: <LOOPBACK... etc
    link/loopbac... etc
    inet 127.0.0... etc
        valid_if... etc
    inet6 ::1/12... etc
        valid_if... etc
2: enp3s0: <BRO[...] mtu 1500 qdisc noop state DOWN group default ...etc
    link/ether b... etc
3: enp2s0: <BRO[...] mtu 1500 qdisc noop state DOWN group default ...etc
    link/ether b... etc

I know it seems to be missing vmbr0 and vmbr1, and they were there before a restart but now they're not. I suspect it has something to do with state DOWN

I've seen some instructions mention editing nano /etc/sysconfig/network-scripts/route-eth1 but I neither have that file or that folder.

I've also seen instructions talking about bonding, but that seems to be for people trying to use two NIC's to get better bandwith, or redundancy. I want to basically use my second NIC to give access to a computer the rest of the household will be connecting, without using the WIFI card the seperate computer has installed. It's slower and spotty at best, and compared to 10GBe, there is no competition.

I'm quite green when it comes to code, but I can understand instructions if they don't require too much "interpretation". So I tried following these instructions How to add second NIC, but I don't understand some of his terms, or what settings I need to sub in for my own. Which IP address and name is for which NIC?

Help?

 

[DR4GON]

The results of systemclt status networking is

error: lo: lo: up cmd '/etc/network/if-up.d/route' failed: returned 127
error: vmbr0 : (enp2s0: up cmd '/etc/network/if-up.d/route' failed: returned 127
error: vmbr1 : (enp3s0: up cmd '/etc/network/if-up.d/route' failed: returned 127
warning: vmbr0: interface not recognised - please check interface configuration
warning: vmbr1: interface not recognised - please check interface configuration

So I guess I can start there.

Oh this was related to something someone said to do, but it must be wrong, either I set it up wrong or I'm using it for the wrong thing.

#!/bin/sh
route add -net 192.168.0.0/24 gw 192.168.0.2 dev enp3s0

It was meant to give enp3s0 an IP so I could then connect to that with the Ubuntu computer. Was I wrong? Should I have used a different IP?

 

[DR4GON]

Okay, I have returned access to the GUI, but the sharing of the second NIC is still outstanding.

I just don't want to have to default to visualizing a full Ubuntu install (the only way I know how to do what I want to do)