Hi 

I have a router tp-link Archer C9 which always worked as dhcp server in my Network. I have also 2 Network switches (tp-link 8 port easy Smart and 4 port unmanaged) and a NAS server Synology DS920+. Recently I wanted to test the Pi-hole on my NAS. To do this I have disapbled dhcp on my router and turned on on my NAS. It was not working well so I decided to get back and set the Pi-hole as DNS manually on some devices. I have turned off dhcp on NAS and turned on on my router, reset and.... not working. Tried to turn off the NAS, reset everything including all the devices. Only devices with IP reservation connect to the Network. DHCP is turned on, but it has 0 clients and no device get the IP. 

Please help, what can I do to make it Work again.