Hi! I’m new here and hope to get some help.

For at least 5 hours today I can’t connect to https://chaos.social/ (the Mastodon server I’m on). Firefox gives me:

Unable to connect

Firefox can’t establish a connection to the server at chaos.social.

    The site could be temporarily unavailable or too busy. Try again in a few moments.
    If you are unable to load any pages, check your computer’s network connection.
    If your computer or network is protected by a firewall or proxy, make sure that Firefox is permitted to access the web.

From curl I’m getting:

$ curl --ipv4 --verbose https://chaos.social/
* Host chaos.social:443 was resolved.
* IPv6: (none)
* IPv4: 5.9.119.202
*   Trying 5.9.119.202:443...
* connect to 5.9.119.202 port 443 from 192.168.1.45 port 40188 failed: Connection refused
* Failed to connect to chaos.social port 443 after 21 ms: Could not connect to server
* closing connection #0
curl: (7) Failed to connect to chaos.social port 443 after 21 ms: Could not connect to server

It’s the same for http, so not related to TLS.

All other websites work normally, but to this particular one I can’t connect from any device on my home network (I tired a few laptops, phones and our Raspberry PI home server). I tried to restart the router (Zyxel T-56). No change.

I can connect via mobile network or from a VPS in “the cloud”. Also https://www.isitdownrightnow.com/chaos.social.html shows that it’s on-line.

I can think of three reasons, but I’m not a networking guru, so maybe it’s something else:

1. My router blocks it

   That would be surprising, because it has the stock configuration from my ISP and I definitely didn’t tweak anything in last days.

2. My ISP blocks it

   But then it’s the same ISP for wired and mobile connection. The latter works.

3. The server is blocking me for some reason

I’d appreciate help in digging deeper, if only to learn.