SSL
Let’s Encrypt
https://letsencrypt.org/docs/
https://letsencrypt.org/getting-started/
https://weblog.west-wind.com/posts/2016/Feb/22/Using-Lets-Encrypt-with-IIS-on-Windows
How To Secure Apache with Let’s Encrypt on Ubuntu 20.04
Configuring Let’s Encrypt SSL Cert for Apache on Ubuntu 18.04
Let’s Debug
SSL for free
https://www.sslforfree.com/
RapidSSL
https://www.rapidssl.com/
Certbot
https://certbot.eff.org/
https on subdomain
https://se.godaddy.com/community/Managing-Domains/https-on-subdomain/td-p/30668
SSL Server Test
How to disable outdated versions of SSL/TLS in Apache
VPN
https://support.ivacy.com/kb/how-to-configure-pptp-on-your-linksys-router/