Hello,
I have a Mikrotik wAP AC in a school. Today some students (and I) couldn’t connect to it. I checked DHCP leases (before I had to reset the router to be able to connect to it) and realised there were 53 clients. I’m DHCP serving IPs from 192.168.88.10 to 192.168.88.200: so, we have 190 IPs available to be assigned.
Looking at the IPs served by the DHCP server I saw this: IPs served from .10 to .28; then it jumps to .70, give some IPs, jumps again up to .130, gives some more IPs, jumps to 198…
So it seems it’s not giving a lot of IP ranges inside of the .10 to .200 range, so this seems to be the reason why we couldn’t connect to the router.
Do you know how to solve this? I hope I explained coorectly, my english is not the best!
Thank you,
Oscar
Up! Please, can somebody help me?
Thank you,
The jumps are normal. Usually the DHCP server tries to reassign the same IP to the same client. Imagine 5 computer connect (A to E)
A gets IP 10
B gets 11
B disconnects
C connects. It will (probably) get IP 12.
D connects. IP 13.
B reconnects. The DHCP server will try to reassign IP 11 to it.
Usually it only changes when you have more clients than IPs, or if you reset the server and did not configure it to write the leases to flash. Say, a /24 network to 400 students. Split them in two shifts (morning and afternoon), and you have enough IPs to work with. But not enough to keep them the same from one day to another.
Now, why the server isn’t giving enough IPs: What is the lease time You used? Because the DHCP server will not reuse an address before its lease time expires - even if the client is turned off. If you have only 200 IPs, and more than 200 total users, the lease time must be small enough that the server will have free addresses to give.
Are you sure that other IPs are free?
If you want to be sure that the cause of connection not working is the (lack of) IP address assigned, then you should check on the client device.
Usually dhcp-server assign the IPs starting from the highest one (in your case from 200 to 10).