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hecklertm
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Wireless clients slow to dhcp address on all MT versions

Mon Apr 10, 2006 8:28 am

I have used many versions of 2.8 and 2.9 other the last year, and all have shown the same issue. I am still puzzled as to why when a wireless client associates to my MT routers for the first time (or for the first time since having associated with some other router), the clients take way long to aqcuire their ip information via dhcp. It takes long enough that in WinXP, the icon comes up that only a "limited connection" is available. Then about 2 to 3 seconds after that, it immediately gets the ip info and cruises along just fine. I have had this problem with 6 different MT routers, and I hope it is something in my config that I can change to remedy this. I assume not everyone has this same problem because I can not easily find other posts about this.

It is a fairly trivial problem, but it makes my access points seem kind of substandard to first time users... Any advice is greatly appreciated.
 
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normis
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Mon Apr 10, 2006 9:12 am

Enable authoritative in DHCP server:
/ip dhcp-server set <name> authoritative=yes
 
Micat
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Re:

Fri Jul 24, 2015 2:25 pm

Enable authoritative in DHCP server:
/ip dhcp-server set <name> authoritative=yes
My server has authoritative=yes, but still getting of an addres for WiFi client is slow.
 
Ape
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Re: Wireless clients slow to dhcp address on all MT versions

Tue Jul 28, 2015 5:00 pm

Hi,

two things come to my mind:

- if you use input rules on firewall, allow input for port 67 and 68 UDP (https://en.wikipedia.org/wiki/Dynamic_H ... #Operation)
- is your DHCP server acting on a bridge interface which has STP enabled? STP takes time to establish loop free connection, this takes 15 seconds (default), in this time a client won't get an IP address from DHCP because the physical interface is down during this time. (https://en.wikipedia.org/wiki/Spanning_Tree_Protocol)

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Micat
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Re: Wireless clients slow to dhcp address on all MT versions

Sat Aug 08, 2015 9:23 am

if you use input rules on firewall, allow input for port 67 and 68 UDP
The delay is still present. When turning phone's WiFi on, it waits several seconds on "getting IP address" phase, and finally, when address is got, rule's counter is incremented.
is your DHCP server acting on a bridge interface which has STP enabled? STP takes time to establish loop free connection, this takes 15 seconds (default), in this time a client won't get an IP address from DHCP because the physical interface is down during this time.
The setting was "rstp". Changing it to "none" did the trick. What if I do not want to disable STP?
 
Ape
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Re: Wireless clients slow to dhcp address on all MT versions

Mon Aug 10, 2015 10:54 am

Hi Micat,

I'm glad to hear your problem is solved.
The setting was "rstp". Changing it to "none" did the trick. What if I do not want to disable STP?
It's a good question. IMHO, the timeout for getting an IP address by DHCP is configured to short on the devices - I know you won't be able to change this on most mobile devices :-( RSTP takes less time, but appareantly still to much for the devices trying to get an address by DHCP.

I tend to propose to not use STP/RSTP on the bridge bridging the wifi with the ethernet ports.

Ape
 
NoahDarby
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Re: Wireless clients slow to dhcp address on all MT versions

Mon Dec 19, 2022 5:42 am

Even with RouterOS 7.6 my two MikroTik Wifi APs were killing me on the time it takes to connect. Setting the STP to NONE on the bridge fixed this. Thanks for pointing it out.

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