My router is running hotspot with DHCP configured to lease addreses from 192.168.0.2-192.168.0.254. I have about 150 clients. They get authenticated through hotspot and they get IP addreses from DHCP-pool of the hotspot. A strange thing is happening, many clients when they power on the PC-s they are getting an IP-adress like 192.168.100.129 and no gataway but in my router there is no ip address like 192.168.100… at all. so I have to go to the clients and type IP addreses. This is not happening with all clients and allso sometimes the same user is working fine but after that he turns of the pc and turn back on again he doesnt get a lease automatically. Anyone can help me with this please
Router OS is 2.8.26
Anyone alive in this forum
Are you sure there is no other DHCP server on your network or some subnetwork where these clients connect? Try some tool like this.
Hi Acim
No there in no other dhcp server running on my router I allso tried to change DHCP class like trying with 192.168.200.2-254 but it is the same problem, I have some users they never have problems there are some they do but no allways. Allso the IP adress 192.168.100… they are getting is only ip address and subnet mask no gataway and no dns
what does you mikrotik say under /IP DHCP-server leases?
Do you see the cleint connected in the wireless registration tab?
Yes client is shown in registration table and allso in dhcp lease I see that a lease has been offered to client bridge-antenna but not to his pc
what is the client hardware?
PC with windows xp and ovislink client AP connected to a pacwireless panel antenna 2.4 ghz 802.11 B
these look cool.. how mnuch do they cost? anyway.. what mode are they in? I know some CPEs do DHCP and NAT on the inside.. and if everyone is getting the same IP.. it might be coming from the ovislink See if you can check into the cleints hardware for the NAT and DHCP settings..
Surfnet do you have msn account where we can talk online my address is vali61@hotmail.com
or maybe someone plugged a SOHO grade router in backwards and it’s internel DHCP server is listening for DHCP requests on ur network.. not good 
Surfnet
the default ip of the client bridge is 192.168.100.252. The client hardware is in client mode and the dhcp client in bridge is enabled so the client hardware is getting a lease from the main router but I dont know why the pc in not doing it (sometimes yes and sometimes not). I allso tried with dhcp disabled in client bridge with static ip address in bridge but still the pc doesnt get the lease. The client bridge has no NAT option
Everything was fine with OS 2.8.22 but since I upgraded to 2.8.26 and now to 2.8.28 Im experiencing this problem.
No there is no soho router backward.
Does your CPE hardware have an internal DHCP server?
The only way to find out where its getting that IP address is to take one of the malfunctioning CPE’s or the clients with the problem and run a packet capture utility to see what’s goin on while the client trys to get an IP address.
It sounds like theres something on your network that is running DHCP other than your Mikrotik router. The fact that your CPE device has a default address on the 192.168.100.0/24 network and your users are reporting problems and recieveing an IP address on that same network (192.168.100.0/24) would lead me to believe that your CPE devices have some kind of DHCP server enabled.. or at least one of them does.
OR your CPE device is not a transparent bridge and doing some kind of MAC-NAT that’s confusing the DHCP/Hotspot server.
anyway those are just a few things that came to mind…
Yes the client CPE-s have dhcp server but it’s disabled
Do you think that let’s say on of the client has gone into CPE and switched on DHCP server do you think that that CPE will be available to couse this since all the client connects to the mikrotik hotspot through wireless infrastructure and I think that the hotspot and mikrotik firewall rules should prevent this to happen.
Do you have Default Forward turned on? that would allow a rouge DHCP server from a client netowrk to give DHCP to you other clients.
The forward chain looks like this:
0 ;;; limit access for unauthorized hotspot clients
in-interface=metro action=jump jump-target=hotspot-temp
1 ;;; account traffic for authorized hotspot clients
action=jump jump-target=hotspot
2 ;;; !!! Check for well-known viruses !!!
action=jump jump-target=virus
Input chain looks like this:
0 ;;; account traffic from hotspot clients to hotspot servlet
in-interface=metro dst-address=:80 protocol=tcp action=jump
jump-target=hotspot
1 ;;; accept requests for hotspot servlet
in-interface=metro dst-address=:80 protocol=tcp action=accept
2 ;;; accept requests for local DHCP server
in-interface=metro dst-address=:67 protocol=udp action=accept
3 ;;; limit access for unauthorized hotspot clients
in-interface=metro action=jump jump-target=hotspot-temp
4 ;;; !!! Check for well-known viruses !!!
action=jump jump-target=virus
no-no.. I mean on your wlan interface.. not the firewall. In the wireless tab you ahve Default authenticat, Defualt forward.. and Hide SSID..
is default foward on or off?
Sorry, yes both default forward and authenticate are enabled, hide ssid is disabled
disable default forward
Hi Surfnet
I disabled the default forward and tested the network for 3 days and everything is perfect now. I appriciate very much your help becouse you really solved my problem, I will be glad to be able to help you with any issue in the future.