The server is running at my friends house who has a fiber connection. When we face these connection issues, it does not necessarily mean that all of us cannot access Jellyfin but often times only a couple of us cannot access (same error as if you mistype a web-address, so it cannot resolve the domain name). During these periods of connection issues, the internet connection of my friend is working completely fine. I have a script running that constantly sends the current IP address to the dynDNS provider. I also looked into how often our ISP changes the IP address and it is not very often and not during these issues.