Dell U2424H does not connect to laptop

After unboxing I connected the Delll U2424H monitor to multiple laptops (Hp, Macbook) with the supplied USB-C to USB-A cable, with an aftermarket USB-C to USB -C and with a DP to HDMI cable without success. The monitor turns on, I access the menu, but the only message I can see that it cannot detect any input sign after both monitor and laptop turned on. Shall I return it or is there anything still to try? Usually monitors are automatically recognises the connected laptops without intervention so it is strange for me. Any tips? thanks