FYI, the problem with Vista is TLS version support, modern websites require newer TLS versions(TLS 1.3 and TLS 1.2) that is not available on Vista.
"TLS 1.1 and TLS 1.2 are not available in Windows Vista, but you can enable TLS 1.1 and 1.2 on Windows Vista using the KB4056564 update patch for...
Most hosts offer some type of site builder, you current hosts could also.
WordPress and Elementor (WordPress plugin - Web builder) on a subdomain for example, staging.yourdomain.com will allow you to play around with WP and the free version Elementor in order to see if it will work for you...
Unfortunately from a technical perspective(at least currently), you somehow used the Mweb SMTP settings, trying to get anything else working would be futile, and at least not a long term solution, have you tried smtpauth.mweb.co.za with the above ports and smtp authentication enabled?
This will cause all sorts of SPF/DKIM/DMARC issues, why do you not use the mweb.co.za SMTP settings, this will be the solution, or get your own domain and email address and use that and set a forward on your mweb email address to your domain email and be sorted for life?
You will also not be...