I have three local domains for my Nginx Proxy Manager running on a VPS, for my self-hosted Nextcloud and my Proxmox-WebGUI both running on my local Homeserver. They follow the scheme service.dataprolet.duckdns.org.
Now I use Uptime-Kuma to monitor my services including the three domains and for some reason those three domains constantly time out after 48 seconds. I already set up the retries to 3, but to no avail.
I also use Pi-hole and Unbound and thought, that might be an issue, but testing my DNS using dig, mtr, traceroute, nslookup and host all returned normal values and no errors.
Does anybody have any idea what could cause this? I'm kind of clueless at this point. Thanks in advance!
EDIT: I don't get it.
I can't ping duckdns.org on my home server. I only get 100 % packet loss. I can open the website in my browser though. I also can't ping www.duckdns.org, which redirects to appservers-duckdns-prod-1630339571.ca-central-1.elb.amazonaws.com. Also gets 100 % packet loss.
I've added duckdns.org to my Uptime-Kuma and it got flagged as down because timeout of 48000ms exceeded but my other domains using DuckDNS were unaffected.
I added another local domain to Uptime-Kuma to see the differences of having ignoring SSL errors tuned on or off and the number of retries:
Nextcloud
Ignore SSL error = false
Retries = 2
Proxmox
Ignore SSL error = true
Retries = 1
VPS
Ignore SSL error = false
Retries = 1
Homepage
Ignore SSL error = true
Retries = 2
Throughout the day only the newly added Homepage got flagged as down for 5 times. The 3 others were up the whole time.
Yes, Uptime-Kuma is running on the same domain as the other services, except the Nginx-Proxy-Manager, which runs on a VPS which I access via WireGuard.
And yes, I'm using Docker. I tried curl'ing one of the domains from the Uptime-Kuma container and got the folllowing error:
curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to service.datenprolet.duckdns.org:443.
So thanks, now I have an idea about what I should investigate.
Are uptimekuma and whatever you're trying to monitor on the same physical hardware, or is it all different kit?
My first feeling is that you've got some DNS/routing configuration that's causing issues if you're leaving your local network and then going through two layers before coming back in, especially if you have split horizon DNS.