Asus DSL-AC750 dhcp issue - wrong subnet ip

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mcgyver83

Occasional Visitor
Hi all,
I have an Asus DSL-AC750 modem router.
Each day I have to physically restart it due a strange issue related to dhcp.
During the day at not fixed time, devices get a bad ip from a different subnet than the router so devices aren't reachable anymore.
Instead of something like192.168.0.x the get 192.168.101.1 or similar. This doesn't happen at fixed time, so I find out that issue happened when I try to use smartTV, media server and smartphone not connected to wifi.

Checking router log maybe I found something strange: ICV Error.
These log lines have a timestamp suitable for the begin of the issue.


Dec 7 12:01:55 router.asus.com kernel: DROP IN=ppp80 OUT= MAC= SRC=45.129.33.176 DST=79.34.218.5 LEN=40 TOS=0x00 PREC=0x00 TTL=245 ID=5913 PROTO=TCP SPT=50706 DPT=41897 SEQ=2782622737 ACK=0 WINDOW=1024 RES=0x00 SYN URGP=0
Dec 7 12:01:56 router.asus.com kernel: AP SETKEYS WPA2 MAC=28:66:66:E6:DB:90
Dec 7 12:02:18 router.asus.com kernel: AP SETKEYS WPA2 MAC=28:66:66:E6:DB:90
Dec 7 12:02:18 router.asus.com kernel: AP SETKEYS WPA2 MAC=C0:97:29:6A:39:2A
Dec 7 12:02:18 router.asus.com kernel: )
Dec 7 12:02:18 router.asus.com kernel: AP SETKEYS WPA2 MAC=10:A4:BA:88:AC:12
Dec 7 12:02:20 router.asus.com kernel: ICV Error
Dec 7 12:02:21 router.asus.com kernel: SYN URGP=0 OPT (020405B40677030801010402)
Dec 7 12:02:23 router.asus.com kernel: ICV Error
Dec 7 12:02:26 router.asus.com kernel: ICV Error
Dec 7 12:02:29 router.asus.com kernel: ICV Error
Dec 7 12:02:32 router.asus.com kernel: ICV Error
Dec 7 12:02:35 router.asus.com kernel: ICV Error
Dec 7 12:02:38 router.asus.com kernel: ICV Error


I can avoid the issue setting manually ip,netmask and gateway but not all devices allow this.
Do you have any hints?
 

OzarkEdge

Part of the Furniture
Hi all,
I have an Asus DSL-AC750 modem router.
Each day I have to physically restart it due a strange issue related to dhcp.
During the day at not fixed time, devices get a bad ip from a different subnet than the router so devices aren't reachable anymore.
Instead of something like192.168.0.x the get 192.168.101.1 or similar. This doesn't happen at fixed time, so I find out that issue happened when I try to use smartTV, media server and smartphone not connected to wifi.

Checking router log maybe I found something strange: ICV Error.
These log lines have a timestamp suitable for the begin of the issue.


Dec 7 12:01:55 router.asus.com kernel: DROP IN=ppp80 OUT= MAC= SRC=45.129.33.176 DST=79.34.218.5 LEN=40 TOS=0x00 PREC=0x00 TTL=245 ID=5913 PROTO=TCP SPT=50706 DPT=41897 SEQ=2782622737 ACK=0 WINDOW=1024 RES=0x00 SYN URGP=0
Dec 7 12:01:56 router.asus.com kernel: AP SETKEYS WPA2 MAC=28:66:66:E6:DB:90
Dec 7 12:02:18 router.asus.com kernel: AP SETKEYS WPA2 MAC=28:66:66:E6:DB:90
Dec 7 12:02:18 router.asus.com kernel: AP SETKEYS WPA2 MAC=C0:97:29:6A:39:2A
Dec 7 12:02:18 router.asus.com kernel: )
Dec 7 12:02:18 router.asus.com kernel: AP SETKEYS WPA2 MAC=10:A4:BA:88:AC:12
Dec 7 12:02:20 router.asus.com kernel: ICV Error
Dec 7 12:02:21 router.asus.com kernel: SYN URGP=0 OPT (020405B40677030801010402)
Dec 7 12:02:23 router.asus.com kernel: ICV Error
Dec 7 12:02:26 router.asus.com kernel: ICV Error
Dec 7 12:02:29 router.asus.com kernel: ICV Error
Dec 7 12:02:32 router.asus.com kernel: ICV Error
Dec 7 12:02:35 router.asus.com kernel: ICV Error
Dec 7 12:02:38 router.asus.com kernel: ICV Error


I can avoid the issue setting manually ip,netmask and gateway but not all devices allow this.
Do you have any hints?

If you have not reset the firmware before configuration from scratch, I would try that first.

Googling kernel ICV Errors finds discussion of WiFi encryption and also a bug fix in another Asus DSL router:

ASUS DSL-N17U Router Firmware Update 1.1.2.3.224 Driver (techspot.com)

So, maybe its a firmware issue.

OE
 

mcgyver83

Occasional Visitor
Many thanks

I already tried a restore factory but nothing changed :(
I will try to get in touch with Asus support
 

ColinTaylor

Part of the Furniture
What firmware version are you using?
 

ColinTaylor

Part of the Furniture
Do you have any other devices on your network that might be running a DHCP server? e.g. old routers or access points.
 

mcgyver83

Occasional Visitor
I have an ethernet connected access point for wifi network at 1st floor and a wifi range extender (so wifi connected to the router).
I set dhcp off on these 2 extra devices. But I tried also with them unplugged, so only the router active and the issue happens, so AP and Extender aren't responsible for this issue :(
 

mcgyver83

Occasional Visitor
Got in touch with Asus support.
They told me to reset and keep the default network 192.168.1.x and check if it happens again.

Going to test during Christmas time :)
 

mcgyver83

Occasional Visitor
First answer from support is to restore the modem and keep the 192.168.1.x network as it is for default settings but no luck... same mess after a couple of hours...
I had to set static ip in all the devices that allow this kind of setting in its config..

Let's wait again for asus support :(
 

mcgyver83

Occasional Visitor
I tried the firmware restore tool from Asus but no luck.
As soon as I started removing static ip config from devices network settings the router started writing "ICV Error" in the log and it assigned ip address from 169.x.x.x instead of 192.168.1.x.

I cannot understand the meaning of "ICV Error" :(
 

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