How to explain to client we need to change server?

My client has a (static) website that is on a windows server. I am going to build them a completely new site. But I need them to switch to a LAMP setup. But I am unsure how to explain this to a client?

Hi,

I’m going to be building your site as we discussed and one of the things that we need to discuss is that the solution that I will be implementing cannot be run on your current server, so we’re going to need to switch your hosting. I’ll make all the necessary arrangements and ensure the transfer goes smoothly for you.

Is that ok with you?

Thanks.

alternatively, you inform them that the hosted solution will reside on your hosted environment and then when you are finished, you switch the DNS A records from their current provider to yours.

unless of course they have internal hosting, in which case you will need to speak to their IT manager first and ask if its even possible to switch over to LAMP (or at a pinch WAMP). This should be done before contracts are drawn up in case you need to amend the price or pull out due to their hosting limitations.