I have a raspberry pi that hosts a web server and has a DDNS registered through no-ip. I just had an issue connecting to my webserver because a certificate appeared to be installed on this server that actually corresponded to the domain name vlad.cool. Changing from HTTPS to HTTP did nothing, as the server appeared to forcefully upgrade my connection. After 10 minutes, this issue disappeared on its own.
I've inspected connection attempts to my raspberry, and all successful ones seem to have been me connecting. SSL was also disabled for my apache server.
What could have caused this? Was it an attack on my local network, or my raspberry? I have no default passwords anywhere.
I had no such issues with other websites, both HTTP and HTTPS.