Cannot verify Server identity - m.hotmail.com - I keep getting this at least once a week HELP PLEASE

Since June i keep getting this message at least every Tue/Wed morning I wake up to it. I have to reset network settings and restart iphone and ipad. I have gone to DETAILS on the message but it only gives me a very long info page but no where does it allow me or give me an option to TRUST CERTIFICATE. I have gone to my settings CERTIFICATE TRUST SETTINGS but there is nothing there to trust. I have never loaded any certificates would not even know how. I have removed my email account a few time now. The only changes in my house are the install of NBN but as I said I have reset the network settings every week since June. Please help as Apple and Microsoft has been unable to help me with this. My ipad runs on either home wifi - Iprimus or Telstra sim, my iphone runs on home wifi Iprimus or Voda sim.