Error connecting to adapter/inverter

[Vanginger]

Hi everyone
First time user here. I have a EW11a connected to my inverter and network. I have followed the instructions on Github for both Tony's and Nathan's addon.. I have also briefly tried Modscan 64
None of them connect, which obviously makes me doubt the connection between the inverter and EW11a.
Our solar was fitted 2 weeks ago, the installer has been doing it over 20 years and said he had put RS485 wiring in a number of times before. At the end of the install, 2 wires were left coming out of the KH10, labelled RS485 (it didn't say which was which). I plugged them into the EW11a, connected to it's local wifi before adding it to my router and network. It was given the address of 192.168.0.61 on our network

I can access the EW11a fine on 192.168.0.61 via the web browser
It has been running for a week and the Serial Port state seems to show traffic, as does the netp (it seems to have found the Home Assistant IP address (192.168.0.7):
Serial Port State
Received Bytes
14284942
Sent Bytes
417728
Failed Bytes
0
Config
9600,8,1,NONE
Received Frames
1796303
Sent Frames
52216
Failed Frames
0

Communication State - 'netp'
Received Bytes
626592
Sent Bytes
0
Failed Bytes
0
Protocol
TCP-SERVER
IP
192.168.0.7
Received Frames
52216
Sent Frames
0
Failed Frames
0
State
Connected

But FoxESS Modbus comes up with:
Error connecting to your adapter or inverter. Ensure the adapter is properly configured and is correctly wired to your inverter (see the setup link above), then try again. Details: Modbus Error: [Input/Output] Modbus Error: [Invalid Message] No response received, expected at least 8 bytes (0 received); No response received after 3 retries, continue with next request

and the other one just has no data in any of the fields.

I think I have done everything right on my side? local port is 502, inverter ID is 247 on the system and inverter.
I have tried swapping the 2 wires around that he left coming out and the received numbers go up a lot more slowly but FoxESS Modbus still comes up with the same issue (admittedly I haven't yet tried that since I installed TonyM1958).
Is my only option left to shut down the inverter and make sure the wires are connected? That is my last resort, just want to make sure there's nothing left to check first - I am sure he will have got it right, he knows more than I do!!

[Will]

I would pop open the com port and double check the pins that it's been connected to vs what the manual says.

[Vanginger]

To do that, do I need to shut it all down like I was sorting the cabling out from scratch?
I never really read that part of the instructions fully as that bit was meant to have been done for me

[Will]

I would turn if off yes as without a com port connected you'll see a meter fault.

[Vanginger]

Thanks
I'll have a look this week.