traceroute uses UDP by default. Specifying
-p 443 isn’t enough, you should also add
-T for TCP.
Did you run that from your Nextcloud snapd? I have absolutely NO idea how snapd works, so it is probably not even possible to run
curl from “inside” the Nextcloud snapd. But for some reason, it can’t resolve the hostname.
There seems to be an Issue on the Nextcloud GitHub regarding this error: https://github.com/nextcloud/nextcloud-snap/issues/178 Please read it and try one of the things mentioned there.
There are a lot of suggestions, commands et cetera in that Issue. If you just tell us “it doesn’t work”, I can’t help you further, because this really looks like a Nextcloud snapd issue to me. If you have a specific command with a specific error, perhaps we might be able to help you.