Connection to App store failed. Also problem with Mail and iTunes
I have 2 iMacs and 2 iPads on 3 of them I can download updates from the App Store and they work properly on all programs, but on 1 iMac the App Store window comes up but stays blank.
When going to "Store" "view my account" it asks for the password (which I know is correct) but I get the answer "connection failed".
Trying to connect to iTunes I also have following problem :
after the cancel I get the next window as follows :
And as a problem never comes alone I was unable to despatch this morning an email from my usual server getting following message :
As I'm prudent I did not try to connect.
I was however able to send the related email using my outgoing iCloud.com server instead of the me.com server
I presume all problems are related to each other but I have no idea how to overcome them on this particular iMac (an Intel Core 2 duo running OSX 10.9.5) considering that the problems don't exist on my second iMac nor on the 2 iPads.
To my knowledge they all use the same Apple ID and outgoing servers.
I would appreciate if anyone could help.
Thanks beforehand.