Please fill out the fields below so we can help you better. Note: you must provide your domain name to get help. Domain names for issued certificates are all made public in Certificate Transparency logs (e.g. crt.sh | example.com), so withholding your domain name here does not increase secrecy, but only makes it harder for us to provide help.
I ran this command: I tried creating a certificate through Synology DSM.
It produced this output: Failed to connect to Let's Encrypt. Please make sure domain name is valid.
My web server is (include version): Synology DSM 6.2.3-25426 Update 3
The operating system my web server runs on is (include version): Synology DSM 6.2.3-25426 Update 3
My hosting provider, if applicable, is: Not applicable
I can login to a root shell on my machine (yes or no, or I don't know): yes
I'm using a control panel to manage my site (no, or provide the name and version of the control panel): Synology DSM 6.2.3-25426 Update 3
The version of my client is (e.g. output of certbot --version or certbot-auto --version if you're using Certbot):
Ports 80 and 443 were closed when renewal was needed. Now I can't create new certificates.
I searched the web and tried few solutions which didn't work. One of them was to delete all certificates and start new but now I can't create new cert as well.
Ports are open properly. I checked it with https://canyouseeme.org/. Also this worked before when I was creating a certificates in the first place.
If any additional info is needed, I'm happy to provide. Thank you for the help.
Does it actually say "Failed to connect to Let's Encrypt."? Because that implies your NAS can't reach out to the Let's Encrypt server all together.
While @JuergenAuer has a point that a redirect from HTTP port 80 to port 5000 would make any http-01 challenge fail (the port 80 -> 5000 redirect is still present by the way), it seems you're not even getting to the validation step anyway, as your NAS can't reach Let's Encrypt to begin with.