Your ISP's DHCP is Not Fucntioning


My fiber connection was working until yesterday afternoon when my router showed me the message "Your ISP's DHCP is Not Fucntioning". I have already tried to power cycle the modem and router. Router is Asus GT-AX11000.


12 kommenttia

Käyttäjätaso 6
Kunniamerkki +19

Hello @SmartBomb and welcome to Telia yhteisö!

Have you tried to take out fiber cable for 15 minutes? At least try if it helps 😁>

Kunniamerkki +12

@SmartBomb@  kirjoitti:

My fiber connection was working until yesterday afternoon when my router showed me the message "Your ISP's DHCP is Not Fucntioning". I have already tried to power cycle the modem and router. Router is Asus GT-AX11000.


Not sure if I remember correctly, but it might be Asus which has "aggressive DHCP" setting which is non-standard, incompatible way to handle DHCP. Someone had this turned on and it triggered some kind of security feature in Telia's side, which means the router was kicked off from the network. Not sure how it exactly works but that "aggressive" sounds like it's flooding DHCP request all the time, which could lead to customer blocking in DHCP server firewall.

@SINAD I'll give it a try, but it's strange it would trigger something after 2 years of use with the same settings

How long did it take for the change to take affect in Telia's end?

Käyttäjätaso 3
Kunniamerkki +9

@SmartBomb@  kirjoitti:


How long did it take for the change to take affect in Telia's end?






I don't know the exact time and our network specialist are coming back to work tomorrow so can't ask this right away.

If your router is flooding extremely the DHCP request, the whole subscription can be shut down. If this happens, you will receive and email and SMS text about that. Usually this is happened because of malware or virus within own devices.

I recommend you to test the connection without router if possible. Can you get an IP-address/connection if you connect your own devices (for example laptop) straight to fibre modem?


@SINAD@  kirjoitti:

@SmartBomb@  kirjoitti:

My fiber connection was working until yesterday afternoon when my router showed me the message "Your ISP's DHCP is Not Fucntioning". I have already tried to power cycle the modem and router. Router is Asus GT-AX11000.


Not sure if I remember correctly, but it might be Asus which has "aggressive DHCP" setting which is non-standard, incompatible way to handle DHCP. Someone had this turned on and it triggered some kind of security feature in Telia's side, which means the router was kicked off from the network. Not sure how it exactly works but that "aggressive" sounds like it's flooding DHCP request all the time, which could lead to customer blocking in DHCP server firewall.


Normally aggressive dhcp settings renew ip lease faster not non-standard way. 

@HenriLie Tried direct connection to modem. No connection.

Kunniamerkki +12

@sevk_@  kirjoitti:

Normally aggressive dhcp settings renew ip lease faster not non-standard way. 


You cannot make it faster. The leasetime is set to DHCP server config and in this case it's 1200 seconds. Client/customer side cannot change this so there shouldn't be any settings for this at all. The DHCP client has to renew the lease when 50% of lease duration is expired, so in this case once per every 600 seconds. When the renewal is started at 50% point of lease duration, there's always  plenty of time to retry the renewal if the server is overloaded or there's communication issues. So there's no need to make it any faster than that and any attempts to do so may lead to some kind of ban. I remember that someone had similar issues in this forum and the root cause was that setting.

Käyttäjätaso 3
Kunniamerkki +9

@SmartBomb@  kirjoitti:


@HenriLie Tried direct connection to modem. No connection.






Okay, it seems there is something else problem then. Please contact us via chat (after log in) and we can check this subscription/connection more closely.


@SINAD@  kirjoitti:

@sevk_@  kirjoitti:

Normally aggressive dhcp settings renew ip lease faster not non-standard way. 


You cannot make it faster. The leasetime is set to DHCP server config and in this case it's 1200 seconds. Client/customer side cannot change this so there shouldn't be any settings for this at all. The DHCP client has to renew the lease when 50% of lease duration is expired, so in this case once per every 600 seconds. When the renewal is started at 50% point of lease duration, there's always  plenty of time to retry the renewal if the server is overloaded or there's communication issues. So there's no need to make it any faster than that and any attempts to do so may lead to some kind of ban. I remember that someone had similar issues in this forum and the root cause was that setting.


It is not faster. That asking new lease shorter time. Not after half way lease time. If aggressive mode can't get answer for leasing asking that make after that shorter waiting time new question. Normally waiting time for after zero answer is like 3 second, aggressive mode ask again like after 1 second. Then new 1200 seconds start again. There is no need ask new lease after 600 seconds. 

 

I have problem get ip lease when I use Asus without aggressive dhcp. 5-6 years and three Asus routers. 

Kunniamerkki +12

@sevk_@  kirjoitti:

It is not faster. That asking new lease shorter time. Not after half way lease time. If aggressive mode can't get answer for leasing asking that make after that shorter waiting time new question. Normally waiting time for after zero answer is like 3 second, aggressive mode ask again like after 1 second. Then new 1200 seconds start again. There is no need ask new lease after 600 seconds.


Yep - sounds very non-standard way to handle DHCP... No wonder that this kind of routers are banned from network. There's simply no need to use too short timeouts. Telia's DHCP is very reliable and it WILL give you new lease in time and with standard DHCP timeouts. I haven't never noticed any DHCP issues with my Edgerouter ER8pro which uses standard Linux DHCP client. Not even with this 1200 seconds lease time. It's always renewed in time and without any issues. So I prefer you to use the normal DHCP mode to avoid banning.

https://www.snbforums.com/threads/so-what-is-the-point-of-aggressive-dhcp-query-frequency.11738/

 

 

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