Pi-5, NVMe and Mesa

Help.
I'm no linux guru and I'm having trouble finding an installation path the gives me a working system with connection Pi to the Mesa card.
By background I'm a retired electronic engineer turned C++ programmer doing large models and I actually worked for Hitachi Seiki years back until they died.
I have added steppers to a bench top milling machine and I really hoped to get LinuxCNC running on it.
I bought a Pi-5 with an NVMe hat which runs fast and a Mesa 7i95T to do the heavy lifting,
I tried the Pi-5 system image from this site but I can't get it to Ethernet into the Mesa.
I can't get a lot of the Pi commands to work to control the NVMe or the networking although they work on the 'standard' image.
I'm confused as can be and google gives me contradictory sites that often give me command that don't run or generic instructions that I can't trace to concrete things to try.

Is there an ELI5 guide somewhere, or do I have to give up on my current hardware and do it another way? If so what?

Please supply more information "does not work" isn't very helpful.

What IP addresses are you using ?

Have you tried toto configure the pi ?

Have you looked at the announcement thread for the RPi 5 image ?

Keep in mind that the image is somewhat different to a standard Raspbian OS iamge, so a lot of the info you'll find for that is not applicable.

Tommy has given good advice, older PCs a so much better and easier than an RPi to setup for Linuxcnc.

But to help you we will need more information, what have you tried ? What has happened ? Do you have any error messages.

Well I've tried going back to the beginning and starting again too many times to be clear on anything now. I was rather hoping to push it all to one side and implement a 'this worked for me' sequence from somebody. My last hang up was the Ethernet not linking to the Mesa card so I can't talk to all my carefully crafted hardware and the 'usual' Pi functions not being on the prepared image.
I have some documentation on the Mesa card and if I could just get that working I could scramble some code together to read my switches and drive my steppers and make manual milling much easier. Once I get the most basic functionality I can grow it
I have a nice box built with stepper drivers, PSUs, Mesa card and the Pi-5 with screen, touch and USB connectors and all the stepper hardware and the DRO stuff available (I was hoping to snoop the DRO sensors while keeping it running).
It is perhaps poetic irony for a time served software man to have a software problem but most sets of instructions I see tell me to use commands that even with sudo the Pi says don't exist and one that insists it only works on a Pi4, Others are too global like 'Install RT Kernel'
I am suspecting there is a magic trick or even just the 'right' phrase to put into google to find a working example that at least gets me close.
If the trick is just to buy a mini-pc and put Debian on that (I have Debian on a web server and a laptop), I already have a couple doing other jobs about the house, I can live with it.

Right. I did a new rebuild on a later kernel from the thread LinuxCNC 2.9.2 and 2.93 images for Raspberry Pi 4b & 5
Nobody seemed to be screaming that it destroyed civilisation so I put it on an SD, booted it and flipped it onto the NVMe.

This is with a six inch cat8 cable between the Pi5 and the Mesa.
This is silly. I must be having a senior moment here. The board is definitely jumpered DN DN and the
documentation assures me that that means 10.10.10.10 on 'as delivered' firmware.

cnc@Pi-CNC:~$ ping 10.10.10.10
PING 10.10.10.10 (10.10.10.10) 56(84) bytes of data.
From 10.10.10.11 icmp_seq=1 Destination Host Unreachable
From 10.10.10.11 icmp_seq=2 Destination Host Unreachable
From 10.10.10.11 icmp_seq=5 Destination Host Unreachable
^C
--- 10.10.10.10 ping statistics ---
7 packets transmitted, 0 received, +3 errors, 100% packet loss, time 6150ms
pipe 4
cnc@Pi-CNC:~$ sudo ifconfig -a
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.10.10.11  netmask 255.0.0.0  broadcast 0.0.0.0
        ether d8:3a:dd:b0:cf:14  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 89  bytes 14327 (13.9 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 112  

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
 

down/down on IP address jumpers is 192.168.1.121
down/up is 10.10.10.10 

(W15 down, W16 up on a 7I95T)

(after a power cycle)

Bangs head against the wall.
So simple. 10.10.10.10 is not the default but the EEPROM default. Select the EEPROM.
So now I just need to figure out how to set up the eth0 port on boot and I can start to load Linux CNC.

Thanks for putting up with a dumb ol' 74 year old.
If I get any more stupid I'll have to become a politician.

It's like me when I've edited a firmware file 20 times and can't get things
to work, only to discover later that the file I was editing was not in the build
path...