Just because you get your internet from a particular provider, does not mean that you are limited to using their smtp servers.
Provided you have the settings correct and an email account with the company in question you should be able to use anyone's email settings to send your mail.
Do you have the website address for your hosting provider. I've never heard of freenetnames - although I do remember freenetname, who later became Madasafish and were ultimately taken over by plusnet.
I've used my own domain for some time both with Virgin Media, until 2019 and now BT, and I've never used their servers for sending using my own domain - except when I was confirming how to set up SPF records for other users to be able to send using theirs.
Virgin Media require that
a) You authenticate
b) You set up an app password for your email address in order to use plain text logins. This is to help protect your account.
Their settings do work - one of my fellow VIP's set me up with an app password access in order for me to be able to test Virgin's email servers are working. Can you confirm which email client you are using there?
Tim