Dual boot problem

I am now running win 10 1903 which is ok. I want to install win7 as a dual boot so I formatted an ssd 240gb and installed win home on it. First issue, I could not connect to the internet. My 'net provider is BT and I use their router for fibre broadband. Win7 would not find it no matter what. Next issue, I shut down, connected win 10 drive and drive with win7, chose win7 from the menu and it didn't boot. So shut down and tried it as stand alone drive but win 10 had destroyed the boot sector. Should the win 7 drive have been formatted as a GPT drive or maybe FAT32 /MBR ? Any help would be much appreciated.

Welcome to the forum. That's not clear you removed 10 disk installed 7 on its own disk out 10 back and 7 wouldn't boot. But 10 wouldn't know about 7 so it shouldn't be on any menu? When 7 disk is on its own what errors do you get?

As I understood, Win 10 and Win 7 are on different disks.
Did you detach Win 10 disk before you installed Win 7?

Can you boot Win 10?

First up, thanks for the welcome to your forum. Samuria, I couldn't reply at the time because my computer was refusing to boot at all. It was in use (10) writing docs and started to power off. Whatever I tried - removing everything in the end except the optical drive, it still shut down after 3 secs. I put the 10ssd back in after 3 days and it magically re-started after a long period (installing updates I think) and I then uninstalled an m-audio legacy midi driver which may have been conflicting. I don't know. I am going to reinstate the driver in a few minutes as I have never had this happen over 7, 8, 8.1 or 10 until recently. I have now posted my system specs if you are interested. Many thanks for your reply and I'll keep you informed as to progress re. dual boot. I was hoping to get the Microsoft style of menu which was a stark choice between drives at one time, but it worked!

Hi Megahertz, thank you also for relying to my problem.
Would you mind looking at the reply I sent to samuria a few minutes ago?
It explains in detail.

You having hardware issues as it restarts or doesn't start at all.
It can be many things, from PS to MoBo or CPU.
I have my wife's GA-Z87-D3HP with same problem. It isn't the PS as it's running my old Z68 with a i7.
I know that the problem is the MoBo or the i5 (4570k). It began by shuting down once a day and now it shuts down just after a start.
I just bought a second hand Asus Z97 on ebay as I think the GA-Z87-D3HP has failed (it smells burned but I can't find out where it comes from). As I live in Brazil my nephew, that lives in US is bringing to me at the end of the year.
Can't help you.
Only suggestion I can give you is to put the i5 CPU on another LGA 1150 MB to find out if it's the MB that has failed.