

How long did you wait to visit the site after adding it to pangolin? I ask, because if you set it up and go within 30 seconds of saving you may see the cert warning initially. It can LetsEncrypt time to verify a site and issue a cert. it’s usually pretty fast, but I’ve seen it take up to 30 seconds or a little longer.
I’ve hit the same thing where I setup a site through Pangolin and go to it too fast, but if I just close the tab and wait about 20 seconds then go again, it all comes up with a proper cert. hope that helps.
Not knowing what your goal is, I’ll start with this: I had very similar hardware to you, and while I was fine with the Omaha Ui, I just never could get it setup how I needed or wanted. I had the er605v2, 3 eap615 wall WiFi 6 apps, and a switch for PoE from the Omaha line but don’t recall the model. I just finally gave up on it, and moved the er605 and wall WiFi APs to OpenWRT. Setup my network with a dumb PoE switch and 4 VLANs and haven’t looked back. It all just works and I almost never mess with it. I’m not saying it wasn’t a little work initially, but it’s been worth it. I’ve now added a 4th wall WIFI (just download a backup of an existing one, install openWRT and restore to the new one. Change the IP and done.) I added two managed PoE Switches with OpenWRT as well. So it’s allowing me to grow as I need to.