If Cloudron is installed at my.domain.com and the custom domain I'm using with Kutt is dmn.net, what I'm a putting in the alias box?

You have to put dmn.net into the aliases. Note that, for this, first you have to add the domain into Cloudron in the Domains View. This will help Cloudron get a cert and also set up nginx properly after you add it to the aliases.

Does that help?

You have to add it in Cloudron as well. If Cloudron doesn't know about the custom domain, then it won't set up the reverse proxy accordingly. You have to add the custom domain that you added in kutt as an Domain Alias (see doc link above).

So sorry, but I'm still a bit confused.

In the screenshot provided for "domain aliases," the aliases are subdomains of the main Cloudron domain – eg site2.cloudron.club or *.sites.cloudron.club

If Cloudron is installed at my.domain.com and the custom domain I'm using with Kutt is dmn.net, what I'm a putting in the alias box?

Like, even in the screenshot provided for Kutt, it suggests you can use example.com/shortURL, but in the Cloudron docs there's not an example of using example.com in any of the boxes.

We set up the domain in the Kutt settings and then also set up the domain in our domain provider's DNS settings.

You have to add it in Cloudron as well. If Cloudron doesn't know about the custom domain, then it won't set up the reverse proxy accordingly. You have to add the custom domain that you added in kutt as an Domain Alias (see doc link above).

@jordankrueger do you get this certificate issue on the domain in which kutt was installed? If so, do you see the cert error in other apps as well?

No. I only see this issue when attempting to utilize the link we've added in Kutt for the custom domain we've purchased for short links.

We set up the domain in the Kutt settings and then also set up the domain in our domain provider's DNS settings.

If maybe this is related to custom domain inside kutt , then you have to add an Alias in Cloudron . See https://docs.cloudron.io/apps/kutt/#custom-domains