Today, my DHCP client lost DHCP servers twice. It also lost IP address once today.
I unplugged hAP ac2 and plugged it again. Now, it works again. I guess wireless connections were lost too, but I haven’t checked my wireless devices.
Did anyone else have this problem, too?
Stating the software version you’re running is equally or even more important than stating the model.
In 6.42.1, problems of DHCP client which match your symptoms are reported, see the topics dedicated to that version.
My hAP ac2 runs RouterOS v6.41.3
On
What’s new in 6.42 (2018-Apr-13 11:03)
I found
*) dhcp - improved DHCP service reliability when it is configured on bridge interface;
I’ll upgrade RouterOS and come back.
the DHCP client issue seems to have been introduced in 6.42 or 6.42.1. The improvement from changelog you quote seems to address a DHCP server issue.
If I read you right, your hAP ac² was acting as a DHCP client, wasn’t it?
I’m using 6.42.1 on my hAP ac2, and haven’t had any problems with DHCP server or client. My ISP is Frontier neé FiOS, and I have about 40 devices on the LAN. I have APs subtended from the router and am not using the router’s Wi-Fi.
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You can believe it, there is a problem with DHCP Client, I get the issue on RB2011, Hap Lite, Hap Mini and RB951Ui-2HnD.
I have sent packet analyzer files to support, they confirmed and it will be corrected in new release
I meant my desktop’s DHCP client that receives IP address from RouterOS DHCP server. I don’t know whether RouterOS DHCP client has an issue.
OK, in that case 6.42.1 should be the solution as you’ve found yourself.
But try to read your first post as if you were a person not familiar with your home setup 
However, I discovered that DHCP server on wlan1 in station mode cannot receive an IP address from a wireless router after upgrading to 6.42.1
And now I’m lost again. DHCP servers do not receive IP addresses, they hand them out. And how is “wireless router” related to the hAP ac², is the hAP ac² a wireless client of some other router? I’m afraid that we are badly missing a diagram of your network.
Nevertheless, 6.42.1 (or already 6.42) has fixed an issue of dhcp server and introduced an issue of dhcp client.
You cant receive IP’s with DHCP Server, it only issues IP’s to other devices. If you want to receive an IP from another DHCP Server you have to make use of DHCP client
I configured DHCP client on wlan1 in IP > DHCP client
RouterOS DHCP server runs on bridge. wlan1 doesn’t belong to bridge.
My current network configuration is
192.168.80.0/24 on Desktop, Phone <-----> 192.168.80.1 on hAP ac2
192.168.0.2 for wlan1 on hAP ac2 <------> 192.168.0.1 on a wireless router from another company <------> 192.168.0.0/24 on other devices
192.168.0.1 issues the IP address 192.168.0.2 to wlan1 on hAP ac2.
Machines behind hAP ac2 can talk to machines behind the other wireless router.
Weirdly, DHCP client works on ether1 which is the WAN interface. But, it takes many minutes for ether1 to renew DHCP lease.
Now it is clear. To temporarily overcome the broken dhcp client of 6.42.1, note down the gateway and DNS server address(es) you get from the other router by means of DHCP, disable the DHCP client and configure the hAP ac²’s own address, the default route and the DNS servers manually. Once the change log says the issue has been fixed, you can upgrade and revert to DHCP client mode. It depends on the level of your adrenaline addiction whether you should do that once the fix becomes available in an rc version or whether you should wait for a current version.
After assgining a static IP address to wlan1 in IP > Addresses, it works for now.
I’ll keep an eye on https://mikrotik.com/download/changelogs
I stumbled upon the solution to my issue.
The issue was with the DHCP server of 192.168.0.1 on another router.
It was not with the DHCP client on wlan1 on RouterOS.
After upgrading the other router, the router’s DHCP server started gradually refusing to issue DHCP leases.
The problem was that old configurations were incompatible with the new OS of the router.
The fix was factory reset of the other router, followed by manual configuration.
Now, there is no problem. I don’t have to wait for a new release of RouterOS.
I’ve never met a router I liked that defaulted to 192.168.0.0 or 192.168.1.0! [emoji38]
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Unfortunately, the issue became worse. The DHCP client on wlan1 keeps searching for a DHCP server forever.
I upgraded RouterOS from 6.42.1 to 6.42.2, but the issue persists.
My smartphone doesn’t have a problem with receiving an IP address from the wireless router which wlan1’s DHCP client is supposed to receive an IP address from.
Never had any issues with DHCP on hAP ac2 on 6.41.3. I suspect your issues have little to do with the router.
We know for a fact that 6.42+ introduced new DHCP issues. So, that may not help you.
However, you could either switch to firmware version Bugfix (uses mainly by businesses) or latest Release Candidate (testing).
I tried bugfix, and wireless didn’t work at all.
I went back to current.
My smartphone can fetch an IP address from a wireless router. My MikroTik hAP ac2 can’t fetch an IP address from the same wireless router.
After rebooting the other router, MikroTik hAP ac2 started getting a DHCP IP address from it. It’s weird.