TP-Link Archer C7 v4 - Trying to get OpenVPN on the router as well as my iPhone

I don't 'think' I need a 3rd party but sometimes I don't think I know anything!
Allow me to explain what I would like to do:
I would like to access my NAS remotely on my iPhone and potentially my work laptop

I used to use the FileBrowser app on my iPhone to access my NAS remotely - I have NO-IP set up and all worked fine

I heard that FileBrowser is not secure and VPN sounds like a great idea

I have Virgin Media as my ISP and the router is set to MoDem mode

I have a TP-Link router flashed with OpenWrt 22.03.3

I have installed WireGuard on the TPLink as well as my iPhone

When I run the VPN on my iPhone, no connection is made

I am sure that it is something simple but I cannot fathom it out
I was thinking that maybe the simple error was that I needed a VPN like NordVPN but would prefer to have a zero cost associated with this task

I do hope that makes sense!!
TiA