Redirects for website that is split on two hosting accounts

Question

I've transferred blog part of website (example.com) to a new hosting and redirected DNS to new host. What is left over is 'special user area' with it's database, which can now be accessed only with an old IP address. Looking for advice here.

1. Is it possible to redirect just one link (login button) to that old IP, with .htaccess?
2. How would I do it?
3. It is a good solution? There is no HTTPS, and I suppose it's hard to obtain one?
4. Is it possible to connect old hosting with a subdomain name (specials.example.com), although main domain (example.com) is pointing to a different IP?
5. Should I just get a new domain name for an old host?
6. Or maybe leave 'special area' at old host with old domain name, and just redirect blog.example.com to a new hosting?

Answer 1

I have deliberately answered these questions out of order so as not to be repetitive - Your earlier questions are more-or-less answered by later answers.

1. Yes, you ca n redirect just one link.
2. You didn't specify the link, so can be specific, but add a line to .htaccess enabling Mod Rewrite, and a second rewrite rule matching the old and new url (google mod rewrite)
3. Yes, you need to set up a subdomain in your DNS pointing to the old IP. As you appear to be using IP based virtual hosting (old site works with IP) you probably font need to reconfigure the old site for a domain to work.
4. You can, but its a more complex/expensive way of achieving 4 - with no benefits assuming you can add a new subdomain as per 4 above.
5. This could work. Its effectively the opposite of 4.
6. Once you have the hosting on a domain/subdomain it should be practical to set up a (free) letsencrypt cert assuming you have a modernish server and shell access. This is not trivial, but its not rocket science either. We can't give more specific info without knowing your hosting platform and level of access. Its worth noting that certs bind to a domain, not an IP address. There are also other ways of acquiring a cert fairly cheaply (us$10/month or so)if your web provider gives you a control panel where you can add a cert but not shell access.