@MR.S 

negative - on the list are clients with fixed IP too... and definitely not all of them - I miss some active clients with fixed IP here

for example Asus has two lists: all client list where is explicitly stated if the IP is fix od dhcp:

and another one where only DHCP leases are incl. rest of lease time:

  @MR.S 

there is for example problem, when I add some new DHCP capable device to the network (e,g, ESP based devices), where I do not know the hostname nor MAC, finding the correct IP will be almost impossible.

On Asus you go to the DHCP list, sort it by Lease time and the with longest one is the right one - you need three mouse clicks from main screen.

yep, I understand, someone can argue, that customer grade router and business grade one is a big difference - indeed, just show me one typical homeuser who will look into DHCP lease table: none, zero, nada............