Sorry to be asking, I read everything similar here, and I’m still stuck.
I have several domains setup the same, with MIAB over on one box and webservers (WordOps) on a separate box. Both boxes are hosted at Racknerds (which is a white label of Amazon, afaict). I have 2 external DNS servers on separate boxes and all the pointers are setup the same for all domains.
I setup the Custom DNS on MIAB to point to the webservers with A records like this
www.domainx.ca A 23.95.xxx.yy [delete]
If I understand correctly, the reason you must do this is so that MIAB won’t hog the www subdomain when it goes to provision LetsEncrypt certificates, since I’m using external DNS under my control pointed to by the domain registrar.
I did not use the auto LE provisioning of WordOps, but instead manually provisioned the LetsEncrypt certificates for each www.domainXXX.ca.
I have setup the WordPress Options|siteurl and Options|home fields with both http:// and https:// during testing with no noticeable difference in outcomes.
I can’t see any differences between the MIAB (box1) and nginx WordOps (box2) webserver configurations! Ugh.
I can’t figure out where the misconfiguration is… any ideas would be welcome.
btw, Mail for all domains is working properly, thanks for great MIAB product