So Ive been trying to do this in my head for a couple days.
Already have a forum website example: Domain(dot)com
Created new VPS to : box.Domain(dot)com
Have the nameserver currently going through digitalocean but the system check after logging into box.Domain(dot)com state that the Domain(dot)com isnt being pointed to the same IP as box.Domain(dot)com
Do I need to move the DNS to the registrar of the domain? (probably yes) ns1.box.Domain(dot)com and ns2.box.Domain(dot)com (if this is the correct solution, how do I change the public IP in box.Domain(dot)com for Domain(dot)com so that normal webtraffic will go to that public IP instead of box.Domain(dot)com
In your set up, that would be expected. It is an error that appears when you use ‘External DNS’ in conjunction with a website located on a different server. This can be safely ignored.
No, not necessary at all.
Just as you likely have it set up now at Digital Ocean. With an A record pointing to the web server.
Now, if you have not yet set up MiaB and this is all theoretical then you need to back up a step and decide if you want Digital Ocean to provide your DNS or if you want MiaB to provide it. There are pros and cons of either method that you choose.
The pros of setting up External DNS with either your domain registrar or other DNS provider mainly focus on the fact that they will not be a potential single point of failure for your DNS. If your MiaB server is down or otherwise offline, you have NO DNS for your domain (unless you are using a secondary DNS provider (which is outside the scope of this post). So with no DNS nobody can reach your website, or send you an email, etc.
The cons of using External DNS are mainly more complexity with your complete DNS solution and more chance of human error in adding mail related entries to your DNS. Focusing on high deliverability of email, MiaB has many mail specific DNS entries that it creates for things such as DKIM, DMARC, SPF, etc. Some of those entries can easily be incorrectly copied to your External DNS system.
Personally, if my domain is only being used for email, and maybe hosting a single static webpage (on the MiaB server) I would opt for hosting DNS on my MiaB server. However, if you are hosting a website on another server or uptime is absolutely critical for your domain, I would prefer to use External DNS mainly due to the fact that you will then have redundancy in your DNS system.