Menu size on Winwos Server

unable to understand your problem.you want to add more menu in you website- that you want to say but unable to do that.is it correct from my side

If you were in Apache server this issue would have been with max_input_vars
https://diywpblog.com/how-to-increase-max-input-vars/

I’m not sure what’s the alternative of this in a Windows Server.

@gordonbarker Did you get any errors while trying to save?

Thanks. When I try to save the whole page just stops working and sometimes when I go back the Menu has disapeared and I have to start all over again – whew!

Try disabling your active installed plugins one by one, see if it resolves. You can also try changing to WordPress default theme like- twentyfifteen and then back to your themes.

Thanks for this advice I will do so and revert. To your knowledge should I be able to add more than 200 menu items in WordPress? I thought that it was an array limitation in WordPress?

Yes, there’s a limitation and you can also override that limitation, Look at this Fix the Custom Menu Items Limit in WordPress

Many thanks ashi, have been able to fix using your link!
Regards
Gordon