Cannot connect to remote computers

PKS_56

I have four remote computers set up on my account. Until recently, I could connect to them all from my mobile app and from my laptop.

I am now only able to connect to two of them. The other two prompt for confirmation and/or password when I initiate a connection.

What can the problem be?

There have been no changes on any of the computers, nor on the mobile app.

PKS_56

Forgot to mention that I have checked the settings on all the computers, which confirm that Full Access has been granted to me. The setting for Connections to Other Computers is also set to Full Access.