cannot verify server identity m.hotmail.com

Hi all, I have had this pop up on both my ipad 3rd Gen and iphone 8plus twice now as well as on my husbands iphone 8plus separate accounts all after last Update this week. I click on details and it shows a very long certificated dated to run out 2026. Then my emails stop working so I have to reset my network settings and do a hard restart and everything works until it pops up again about 5-7 days later. So in 14 days happened twice now. I have been on Apple Chat and called as well and deleted my hotmail email account and reinstalled it Only on ipad to see if this turns up again on both devices or just one. So i left my iphone as is and reinstalled my email on ipad to compare in a week etc. But why is this happening. Apple reports to me that they know of it but it is not their issue. I have logged a call with Outlook but 24 hrs still no contact or reply. Can someone help to stop this and will I eventually not be able to use my hotmail on my iphone and ipad? Apple say gmail, live.com & hotmail same issues reported to them in the past 14 days.