使用修复IP和记录集在其他webhoster上安装带有一个域的WordPress

I have a huge issue that I can't solve:

1. I have a website on HosterA with a subdomain blog.hosterA.com
2. A WordPress blog has to be set up on HosterB (which has a fix IP adress)
3. If I call blog.hosterA.com the browser has to show the WordPress blog on HosterB but the address line has to be blog.hosterA.com/article1 etc.

I have already set an a record from blog.hosterA.com to the IP adress. I can open the blog but it's far to slow and some PHP files are not working.

Could you please give me advice?

Have you considered actually putting the website on HosterB, and just iframe wrapping it on blog.hosterA.com? That would be the most obvious and least intensive solution, IMO.