Explore & discover

Helpful Links

Slow speeds while in DMZ+ mode


Slow speeds while in DMZ+ mode

I have tried three different routers and all of them run at 60 mbps down and around 220 up.  What is wrong with my Pace 5268AC.


First modem:

WNDR3700 - returned


Second Modem:

ASUS RT68U - still have and running dd-wrt


Third and final which I'm keeping:

pfsense box running on a quad core i5 with two Intel Gigabit PCI Network cards.


Long and short is I tried to put all of these in cascaded router mode / DMZ+ and everyone of them gave me the same speeds.  However if I hook up directly to the Pace I get 950 +/- down and 950 +/- up.


What gives?  I have seen other people with the same problem.  The Pace's firewall settings are horrendous, plus I can't monitor my bandwidth using NetFlow like I can with my pfsense.  I'm very close to cancelling AT&T and going back to Comcast.



Chris P.

Message 1 of 68

Re: Slow speeds while in DMZ+ mode


Try checking the duplex setting, see if that is the cause of the issue you are experiencing,

Tony–AT&T Community Specialist

Need help?
Ask a question to get help from the AT&T Community or support from AT&T specialists. If this reply helped you please use Accept solution to mark it as an Accepted Solution.
*I am an AT&T employee, and the postings on this site are my own and don't necessarily represent AT&T's position, strategies or opinions.
Message 2 of 68

Re: Slow speeds while in DMZ+ mode



Thanks I did, tried to put on Auto-Negotiate and chose 1000 Full Duplex, didn't make a difference.  I also ran an iperf test on my pfsense router and all the various clients I have hooked up and am getting between 650-750 Mbps between clients. However speedtest.net and att.com/speedtest both are only showing like 60 Mbps down and 225 or so up.  I am using all CAT 6 Cable, that was the first thing I checked. 




Message 3 of 68

Re: Slow speeds while in DMZ+ mode

Have you guys fixed this issue? I'm facing this issue now. I have the gigabit internet as well. I tried different combinations and everytime, the dmzplus mode drops the speed to 50mbps down and ~200mbps up. I've tried all suggested workarounds (ipv6 disabled, wireless turned off, auto-detect to 100Base and back to auto-detect). All this didn't do any good.


I tried doing this with my mac and my nighthawk router like this:

 - Mac-Nighthawk-Pace (with Nighthawk as DMZ) = no good

 - Mac-Pace (with Mac as DMZ) = no good

 - Mac-Nighthawk-Pace (no DMZ) = I get gigabit speeds

 - Mac-Pace (no DMZ) = I get gigabit speeds

Something is off with Pace DMZ+ mode that causes the internet speed to slow down to just ~50mbps.

Message 4 of 68

Re: Slow speeds while in DMZ+ mode

Same issue here, please tell me there's a fix in the works.

Message 5 of 68

Re: Slow speeds while in DMZ+ mode

Same EXACT issue here. I just got off the phone with support, no help at all. I did a MAC clone and verified that out of DMZ+ mode, I get full GBit. As soon as I enable DMZ+, I'm locked at 50Mb/s down. 


EDIT: Per this thread comment on Reddit, https://www.reddit.com/r/ATT/comments/9nhajt/5268ac_issue_information/e96ykzd, I contacted support. Unfortunately, they do not have any other devices available other than the 5268 (go figure). They're sending me a new one. Hopefully it doesn't have the same firmware.

Message 6 of 68

Re: Slow speeds while in DMZ+ mode

I'm seeing the same issue and I'm 99% sure it's due to an update.  I had been running my own router behind the AT&T gateway for several months without any issues. I had to make a change in the AT&T Gateway but the UI page would never fully load to allow me to make my change.  I had to reset the AT&T gateway and it after the reboot, it rebooted a couple more times.  After I added my router back into the DMZ my speeds dropped to 50mbps.  If I leave my router double NAT'd I get 900mbps.


If someone finds a resolution to this issue please let me know.  I cannot deal with AT&T support because it's a waste of time.  If this issue keeps up I will be forced to cancel my uverse.


Model: 5268AC


Message 7 of 68

Re: Slow speeds while in DMZ+ mode

Wow, and I just thought it was me. DMZ+ has been working fine for years with my pfSense setup, and just in the last few days it's been capped at 50. Sure enough if I Double NAT it now I'm getting full speed. This is absolutely unacceptable.

Message 8 of 68

Re: Slow speeds while in DMZ+ mode

Same here. I usually get 850 mbps give or take, as soon as I enable DMZplus I get capped at 50 mbps. It was working for me for at least a year just fine. So I agree it must be due to a pace modem firmware update. It started happening 2-3 weeks ago for me.


Is there any way to revert to a previous pace modem firmware?


Customer service gave me $50 credit adjustment this month and will be calling ATT every month expecting the credit adjustment until this issue is resolved. 


I first found the issue when I couldn't transfer files over SCP from home to my cloud servers (AWS and Linode). My SSH connections get killed if I try transferring any files larger than 5MB! It's such a pain.


Here are some MTR reports which made me aware the issue was on my side.



Tags (3)
Message 9 of 68

Re: Slow speeds while in DMZ+ mode

Me too!!!  Argg I just wasted an hour or so to figure out the dmz plus is what is limiting my bandwidth to 50mbs.  If I remove it then I get like 800.  


I guess I gotta call their technical support when I get some time.  

Message 10 of 68

Re: Slow speeds while in DMZ+ mode


I confirm I see the same issue here with edgerouter 4 behind 5268AC with firmware DL capped at around 50 Mbps when DMZ+ enabled, and ~ 850 Mbps otherwise (fiber connection).



Message 11 of 68

Re: Slow speeds while in DMZ mode

I called support and they are shipping me a different gateway. Not a 5268ac
Message 12 of 68

Re: Slow speeds while in DMZ mode

I'm dealing with this as well.  I was even testing two identical Datto routers, one in DMZ+ and one using DHCP and couldn't figure out why the one on DHCP was running at line speed and the one in DMZ+ was 50/220.


This is unacceptable garbage (yet again) from ATT.

Message 13 of 68

Re: Slow speeds while in DMZ mode

  I just ran into this as well.   My setup has been in DMZ mode for 1 1/2 years with no issue.  Something has happened in the past few days that introduced this speed issue and general 

gateway instability.

Download Speeds are capped around 48Mbs.  If I change the 'Lan IP Allocation between DMZ -to-  Private IPs with firewall'  I am back to 700-800Mbs.


I first noticed a issue on Friday November 30th.  My security system could no longer get out but everything else seemed to work..  It uses a SIP protocol (voice over IP).   A reboot of the gateway fixed the issue.   Then I started having some issues with discord voice chat and some video streaming.   That is when I noticed the speed dropped into this 40mbs range. 

I also noticed at this point the 'wifi' light on the gateway was blinking when I know I had shut off the wifi at installation time (1 1/2 years ago).  Somehow it had enabled the 5ghz band by itself.

It took forever to get the web page to come up so I could disable it again.   It seems that some of the web pages on the gateway are now getting stuck for 10mins+.   


This feels like a really bad software update.


My gateway information:

Model 5268AC , Hw version 260-2173300 , Software Version


For now I will have to live in non DMZ mode.   I will try to contact support during the week.   I really dread that process.


Message 14 of 68

Re: Slow speeds while in DMZ mode

If you go to dslreports ATT forum there are instructions on how to downgrade to v10.7 which fixes the issue temporarily.
Message 15 of 68
Share this topic
Share this topic

Are you having trouble logging in? Is your email password not working? Let us show you how to Reset your Email Password using myAT&T!

Additional Support