Hello, I have strange issues with DHCP server and leases (x86 router v 4.9).

Client can't get IP adress from DHCP server - Windows reports that duplicate IP address exists on network, even if IP address is new and unused in the network. Plus on Mikrotik DHCP server lease table corresponding IP address is stated as bound (to nothing)...

In server log I see folowing:

15:03:02 dhcp,info DH1 assigned 192.168.3.243 to 00:22:15:56:6B:D4
15:03:02 dhcp,error DH1: failed to add arp entry for IP 192.168.3.243: already have mapping for this IP (6)
15:03:07 dhcp,warning DH1 client 00:22:15:56:6B:D4 declines IP address 192.168.3.243
15:03:07 dhcp,info dhcp deassigned 192.168.3.243 from 00:22:15:56:6B:D4
15:08:26 dhcp,info DH1 assigned 192.168.3.239 to 00:22:15:56:6B:D4
15:08:26 dhcp,error DH1: failed to add arp entry for IP 192.168.3.239: already have mapping for this IP (6)
15:08:30 dhcp,warning DH1 client 00:22:15:56:6B:D4 declines IP address 192.168.3.239
15:08:30 dhcp,info dhcp deassigned 192.168.3.239 from 00:22:15:56:6B:D4
15:17:16 dhcp,warning DH1 client 00:0F:EA:50:1C:01 declines IP address 192.168.0.172
15:17:16 dhcp,info dhcp deassigned 192.168.0.172 from 00:0F:EA:50:1C:01

P.S. If IP is written in network connection IPV4 protocol, then everything goes smoothly without any errors about duplicate entries.

Anyone else has similar problems, which are said fixed in 4.6.

yes even we are facing the same issue but it strange looking yet to a solution.

Please check in interface menu ARP status. Turn off arp-proxy and use 'enabled'. Thats worked for me.