Help with DHCP

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Roach
DD-WRT Novice


Joined: 21 Jul 2007
Posts: 37

PostPosted: Wed Aug 20, 2014 2:45    Post subject: Help with DHCP Reply with quote
So Im kinda a newb at this (forewarning lol) but I just got dd-wrt up and running on my R7000. I read that its best when doing static ips not to do them in the same range as the dhcp ones, so I wanted to 'force' the new IPs onto the 10 devices I had. So in my infinite wisdom I went to the Status -> LAN page and under DHCP Clients I hit the trash can for all my devices. Well now I cant get any back on to the wireless

After some messing around I noticed that if I uncheck DNSmasq it instantly works again. If I turn DNSmasq back on, it drops them. Is there a procedure to get it to work with DNSmasq or what am I missing here?

Thanks all!
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Roach
DD-WRT Novice


Joined: 21 Jul 2007
Posts: 37

PostPosted: Fri Aug 22, 2014 2:14    Post subject: Reply with quote
anyone? thanks
HalfBit
DD-WRT User


Joined: 04 Sep 2009
Posts: 209
Location: AR, USA

PostPosted: Fri Aug 22, 2014 2:27    Post subject: Reply with quote
What do you mean check DNSMasq? The "Use DNSMasq for DHCP" checkbox? I'm pretty sure that shouldn't be on if you have the DHCP Server enabled just above that.

The whole point of the not having static IPs within the DHCP range is because it could potentially cause an IP conflict on your network. For my setup I have DHCP set up for 192.168.1.150-159 (or 10 devices). However, all of my devices that I currently own have a static IP from 192.168.1.100-109 (computers, printers, camera, mobile) and 192.168.1.1-3 (main router and other routers set up as APs).

I'm not sure if you understand the IP conflict idea so I'll give an example for you or anyone else reading that may not know. Lets say you have setup the DHCP pool to be from 192.168.1.100-149 (50 devices), and then you have a computer on the network that you statically set to 192.168.1.101.

Initially you may not have a problem, but lets say you turn the computer off for a week or so. During that time you have 25 other devices that are getting IPs in the 192.168.1.100-149 range, including your phone that was assigned 192.168.1.101.

You then decide to pull out the computer that had been statically set to that same address of 192.168.1.101, but now the computer won't connect because there can only be one device using an IP address--hence you have an IP conflict on your network. That is why you should assign static IPs to devices that are OUTSIDE the DHCP address range.

_________________
R7000 Nighthawk - v24-sp2 (08/07/14) kongac - build 24800M
~~~~~~~~~~~~~~Not Currently Used~~~~~~~~~~~~~~
WRT54Gv2 - V24 STD Build 22118 configured as AP
WRT54Gv8.2 - V24 Micro Build 22118 configured as AP
JAMESMTL
DD-WRT User


Joined: 13 Mar 2014
Posts: 227
Location: Montreal, QC

PostPosted: Fri Aug 22, 2014 3:41    Post subject: Re: Help with DHCP Reply with quote
Roach wrote:
So Im kinda a newb at this (forewarning lol) but I just got dd-wrt up and running on my R7000. I read that its best when doing static ips not to do them in the same range as the dhcp ones, so I wanted to 'force' the new IPs onto the 10 devices I had. So in my infinite wisdom I went to the Status -> LAN page and under DHCP Clients I hit the trash can for all my devices. Well now I cant get any back on to the wireless

After some messing around I noticed that if I uncheck DNSmasq it instantly works again. If I turn DNSmasq back on, it drops them. Is there a procedure to get it to work with DNSmasq or what am I missing here?

Thanks all!


Static ip = ip manually set on device
Address reservation = fixed address reserved for a device and sent via dhcp response

You want address reservations

Basic setup

Setup
Dhcp server enabled
Use dnsmasq for dhcp
Use dnsmasq for dns
Authoritive

Set range

Services
Dnsmasq enabled
No dns rebind

Add device reservations. Outside of range

Enable dhcp on devices

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Roach
DD-WRT Novice


Joined: 21 Jul 2007
Posts: 37

PostPosted: Fri Aug 22, 2014 13:28    Post subject: Reply with quote
Thanks guys. I will check once I get back home tonight. Once thing that I have noticed since unchecking 'Use DNSmasq for DHCP' was that (seemingly) randomly my phone will disconnect from wifi. When I look at the available wifi SSIDs, my 2.4 and 5gig isnt even listed. To resolve I disable and reenable wifi, then it shows and connects. This may be something with my Note 3 but seems coincidental that it began after my unchecking of that box and assigning manual IPs to all my devices. Any thoughts on that?

Thanks
Roach
DD-WRT Novice


Joined: 21 Jul 2007
Posts: 37

PostPosted: Sun Aug 24, 2014 4:13    Post subject: Reply with quote
Quick update--
I had everything you mentioned already on. As soon as I went to recheck 'Use dnsmasq for dhcp', all of my clients got kicked off the router and they cant grab an IP now.

What am I missing? Again, I had gone into the status -> lan page and clicked the little garbage can icon next to each of the clients last week which got rid of them but I cant get them to come back unless I uncheck use dnsmasq for dhcp

Thanks
HalfBit
DD-WRT User


Joined: 04 Sep 2009
Posts: 209
Location: AR, USA

PostPosted: Sun Aug 24, 2014 4:47    Post subject: Reply with quote
What build are you running?

I had a similar problem with trying to set up a guest wifi virtual access point (VAP). Read this forum, its only two pages and see if you are trying to do something similiar, because from what I can tell with what you are describing, you are.

http://www.dd-wrt.com/phpBB2/viewtopic.php?t=267789

_________________
R7000 Nighthawk - v24-sp2 (08/07/14) kongac - build 24800M
~~~~~~~~~~~~~~Not Currently Used~~~~~~~~~~~~~~
WRT54Gv2 - V24 STD Build 22118 configured as AP
WRT54Gv8.2 - V24 Micro Build 22118 configured as AP
Roach
DD-WRT Novice


Joined: 21 Jul 2007
Posts: 37

PostPosted: Sun Aug 24, 2014 14:13    Post subject: Reply with quote
I am running 24800 (like you were when you had the issue) but dont believe Im doing anything related to guest wifi. I can fairly easily upgrade or just do a factory restore since I have done very little modifications to the initial starting point.

I have literally only done the following after loading
-Set wifi SSID names and passwords
-Set DHCP to start at .150
-Set my 10 clients to have static IPs like .100, .101, .102, etc

I then went in and clicked the 'Delete lease' trash icon from Status > LAN page, and could never get the clients to re-establish an IP.

The last thing I did (just messing around) was to uncheck the 'use dnsmasq for dhcp' which made it go to udhcp and then it instantly allowed me static (and non static) devices to grab IPs and work.


At this point, should I do a factory reset or maybe even go to 24865? When I put this in earlier in the week, 24865 JUST came out and I wasnt sure how stable it would be and elected to stick with 24800

Thanks all. Sorry if some of my post shows off how little I know on this stuff Smile
HalfBit
DD-WRT User


Joined: 04 Sep 2009
Posts: 209
Location: AR, USA

PostPosted: Sun Aug 24, 2014 20:03    Post subject: Reply with quote
Ignore the part about the guest wifi with my issue. My devices were unable to get IPs or lost internet connectivity on my main network when I had the three boxes checked on the Basic Settings page: 1) Use DNSMasq for DHCP, 2) Use DNSMasq for DNS and 3) Authoritative-DHCP.

If you read through that other post again you will see how we seem to have the same issues. We both have a mix of static and dynamic IP addressed devices, and we both had to uncheck the two DHCP-related boxes mentioned above to get the static IPs to work.

Personally, if I were in your position and had the time and opportunity to go through and reconfigure the router, I would try 24865M. Worse case you could save your settings now on 24800M so if you have to roll back at least the configuration part would be easy by restoring the settings.

I'm sure that 24865M has some instabilities which are understandable as the DD-WRT devs and users work together to work the kinks out, but for my use, it has been working great for about 40 hours and counting now. DD-WRT is great and will only continue to get better.

_________________
R7000 Nighthawk - v24-sp2 (08/07/14) kongac - build 24800M
~~~~~~~~~~~~~~Not Currently Used~~~~~~~~~~~~~~
WRT54Gv2 - V24 STD Build 22118 configured as AP
WRT54Gv8.2 - V24 Micro Build 22118 configured as AP
Roach
DD-WRT Novice


Joined: 21 Jul 2007
Posts: 37

PostPosted: Sun Aug 24, 2014 22:06    Post subject: Reply with quote
Good point. I will most likely do that. I noticed that kong tends to release every 7 days so Im thinking he may have an update tonight or tomorrow but will keep a look out. Luckily I havent done much in terms of craziness so it wont be too bad

Also just curious but some of the settings you applied, did you get all that info from Kongs website or just searching the forum? Like to turn on the implicit and explicit beamforming, etc. Just not sure where to really start to learn more about all the options (but so its spelled out in more newbie terms)

Thanks for your help!
HalfBit
DD-WRT User


Joined: 04 Sep 2009
Posts: 209
Location: AR, USA

PostPosted: Sun Aug 24, 2014 23:02    Post subject: Reply with quote
I don't mess with the beamforming, because I don't have any devices that will really utilize or benefit from it. We don't do much streaming and absolutely no gaming, so there's really no point for me to use it in my opinion.

As far as the settings go for me, I usually leave everything the default unless I know that 1) it works, and 2) I truly need it.

Just pay attention to the posts specific to the R7000 especially the threads that get created for each new build and you'll pick up on what's working and what's not for people. Some issues are universal, but most are specific to individual's setup and network, so even though some say something's wrong, others will say it's fine.

For me it just ends up being whether I have time to make sure everything is up and running so the family has internet before I leave for work that day/week when I decide to upgrade/update or reconfigure.

_________________
R7000 Nighthawk - v24-sp2 (08/07/14) kongac - build 24800M
~~~~~~~~~~~~~~Not Currently Used~~~~~~~~~~~~~~
WRT54Gv2 - V24 STD Build 22118 configured as AP
WRT54Gv8.2 - V24 Micro Build 22118 configured as AP
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