U2724DE, waking up randomly, MacBook TB

Hello,

I have a Dell U2724DE monitor. I use it with my MacBook via the Thunderbolt port. After the Macbook goes to sleep mode, my monitor also goes to standby mode, but after a while, my U2724DE monitor wakes up with uncertain intervals, states that it is looking for a thunderbolt signal, and when it cannot find one, it goes back to standby mode. This is annoying because it is constant. I have updated the firmware and browsed the settings a bit, but I could not find a solution. Do you have any suggestions?

Thanks in advance for your help.