When I invite people with the link an error message is generated “Sorry the page you are looking for is not found”…
I’m self hosting on a Synology NAS…
AI-generated summary
A user, karriem, is experiencing issues with invitations on their self-hosted Discourse instance on a Synology NAS. When invite links are clicked, an error message is generated, stating “Sorry the page you are looking for is not found.” Moin and karriem narrowed down the issue, confirming that the error occurs when someone tries to use the invite link received in an email. Moin discovered that the invite link uses “http” instead of “https,” which is configured to be forced on the site. simon suggested that the force https site setting might not be enabled, causing links in emails to use HTTP. karriem found that the force https box was checked but not saved, which was likely the cause of the issue.
Welcome to Meta 
Do you see that error after creating the link, or is that error shown when someone tries to use the link?
In answer to your initial question… when the “invite-link” is clicked a message page is returned stating “Sorry the page you are looking for is not found”
the error is shown when someone tries to use the invite link that they receive in email…
Could you share a link?
Bingo!!! I’m curious why the email uses “http” which I have configured to force https???
The emails being received don’t have https…??? did I do something wrong..?
It looks like HTTPS is setup for your site, but it is not being “enforced”. On your site settings page, search for the force https site setting. Enable that setting if it is not enabled. Unless something has changed recently, when force https is not enabled, links in emails sent from Discourse will use HTTP instead of HTTPS.
but it is per that 
Thank you… upon further checking it appears that I checked the box “force https” but failed to hit the green check afterwards!