Internet going down multiple time a day :-(

[Magister]

I have a RT-AX86U plugged on a (Videotron local ISP version) XB7 cable modem. It has work for years on different Merlin version, but since maybe 2 weeks I have frequent drop because of link down. It happens 2-3 times a day, any time, even during the night with no traffic. I tried to connect WAN on 1GB, 2.5GB, it changes nothing. AX86 is the only device on the XB7, I tried all plugs and at one time plugged multiple old routers on them just to check, and when this happens, all the ethernet plugs on the XB7 drop at the same time. Local ISP checked the modem and everything is running fine, no signal problem, nothing.

Where does this comes from? Can it be a XB7 problem? It looks like this problem may have been reported on xfinity forums according to my search but nothing conclusive on the solution as people says even exchanging XB7 does not stop the drop?

WiFi is disconnected on my XB7, I am not in bridge mode so dual NAT. I have a small switch connected to the AX86 but I have the problem even if I disconnect it.

Of course I tried multiple cable, cat5e, 6, 7, all 6ft or less.

Apr 18 06:49:56 kernel: eth0 (Int switch port: 3) (Logical Port: 3) (phyId: 3) Link DOWN.
Apr 18 06:49:56 kernel: ===> Activate Deep Green Mode
Apr 18 06:49:56 kernel: bcmswlpbk0 (Ext switch port: 8) (Logical Port: 8) Virtual link DOWN
Apr 18 06:49:59 kernel: <=== Deactivate Deep Green Mode
Apr 18 06:49:59 kernel: bcmswlpbk0 (Ext switch port: 8) (Logical Port: 8) Virtual link UP
Apr 18 06:49:59 kernel: eth0 (Int switch port: 3) (Logical Port: 3) (phyId: 3) Link Up at 100 mbps full duplex
Apr 18 06:50:38 kernel: eth0 (Int switch port: 3) (Logical Port: 3) (phyId: 3) Link DOWN.
Apr 18 06:50:38 kernel: ===> Activate Deep Green Mode
Apr 18 06:50:38 kernel: bcmswlpbk0 (Ext switch port: 8) (Logical Port: 8) Virtual link DOWN
Apr 18 06:50:42 kernel: <=== Deactivate Deep Green Mode
Apr 18 06:50:42 kernel: bcmswlpbk0 (Ext switch port: 8) (Logical Port: 8) Virtual link UP
Apr 18 06:50:42 kernel: eth0 (Int switch port: 3) (Logical Port: 3) (phyId: 3) Link Up at 2500 mbps full duplex
Apr 18 06:50:46 WAN_Connection: WAN(0) link up.
Apr 18 06:50:46 rc_service: wanduck 1436:notify_rc restart_wan_if 0

 

[ColinTaylor]

The XB7 is rebooting. You need to look there for the problem, not the Asus.

 

[Magister]

The XB7 is rebooting. You need to look there for the problem, not the Asus.

nope, it's right in front of me, light stays white, ISP checked it and it does not reboot nor loss signal. Also the XB7 does not reboot in a few seconds... between the link down and link up sometimes it's less than 10 seconds.
I think my next step is to exchange it under warranty...

 

[OzarkEdge]

all the ethernet plugs on the XB7 drop at the same time.

That seems odd... all ISP gateway LAN ports 'dropping' at the same time(?)

Local ISP checked the modem and everything is running fine, no signal problem, nothing.

Maybe they overlooked an intermittant LAN ports issue and should have swapped in a different modem for 24 hours to isolate it.

OE

 

[heysoundude]

There may not be anything wrong with your gear/line:

You may not have heard, @Magister , but Videotron made some acquisitions that they've finally been approved to integrate by our leaders in Ottawa.

Could it be that Videotron is doing some network infrastructure work near you to reflect this and that's causing brief service drops?
You've asked them about your line, but it seems you haven't asked if there is any system work going on that would affect you.
Try getting past the first level of tech support/customer service people - Supervisors/senior techs may know more than the frontline workers.

Bon courage!

 

[Magister]

Yes all the ethernet ports drop at the same time, I can see in the syslog of multiples routers connected to ports on the ISP modem.

I will rechat with support to see...

 

[amigohd]

i had the same problem. however, only with the 2.5 GbE WAN interface, but since the beginning. several times a day i had the same error message in the log and the internet connection was gone for a few seconds. also on older firmwares. the 1GbE WAN port never had these problems.
I then changed the MAC address of the wan port at random. since then the connection has been stable. and for several weeks there has not been a single failure.

 

[ColinTaylor]

i had the same problem. however, only with the 2.5 GbE WAN interface, but since the beginning. several times a day i had the same error message in the log and the internet connection was gone for a few seconds. also on older firmwares. the 1GbE WAN port never had these problems.
I then changed the MAC address of the wan port at random. since then the connection has been stable. and for several weeks there has not been a single failure.

Clearly your problem is not the same as the OP's.

 

[amigohd]

Clearly your problem is not the same as the OP's.

true. I meant "similar", not same.

 

[Magister]

So, magically, after speaking to my ISP who said that everything was working fine, the random drop stopped... I had 1-3 drop per day everyday, and for 6 days now, no drops at all.

I don't know if they changed something on their modem, it has not rebooted (uptime of 6 days now).

But on my router I tried many things, especially I disabled the "Auto USB Backup WAN" that was ON even if I don't have/use dual WAN, and I set the DHCP option from agressive to normal (but I didn't have the infamous "Your ISP's DHCP does not function correctly"). I kept the same cables as before and same setup in same place, finger crossed!

 

[heysoundude]

Calls to tech support/customer service sometimes get wheels turning in the background, and an issue was discovered and remedied, or some work they didn't tell you about on their network got completed.

 

[Magister]

nope, it happens again, after 2 weeks, I'll contact my ISP

/jffs/syslog.log:May 3 03:19:49 kernel: eth0 (Int switch port: 3) (Logical Port: 3) (phyId: 3) Link DOWN.
/jffs/syslog.log:May 3 03:20:33 kernel: eth0 (Int switch port: 3) (Logical Port: 3) (phyId: 3) Link Up at 2500 mbps full duplex
/jffs/syslog.log:May 3 03:21:33 kernel: eth0 (Int switch port: 3) (Logical Port: 3) (phyId: 3) Link DOWN.
/jffs/syslog.log:May 3 03:21:41 kernel: eth0 (Int switch port: 3) (Logical Port: 3) (phyId: 3) Link Up at 2500 mbps full duplex
/jffs/syslog.log:May 3 09:04:43 kernel: eth0 (Int switch port: 3) (Logical Port: 3) (phyId: 3) Link DOWN.
/jffs/syslog.log:May 3 09:04:46 kernel: eth0 (Int switch port: 3) (Logical Port: 3) (phyId: 3) Link Up at 100 mbps full duplex
/jffs/syslog.log:May 3 09:05:21 kernel: eth0 (Int switch port: 3) (Logical Port: 3) (phyId: 3) Link DOWN.
/jffs/syslog.log:May 3 09:05:25 kernel: eth0 (Int switch port: 3) (Logical Port: 3) (phyId: 3) Link Up at 2500 mbps full duplex

 

[Nick24]

Did you ever get a resolution to your issue? I think we have the same problem: https://www.snbforums.com/threads/rt-ax86u-pro-wan-disconnect-every-36-hours.91841/

 

[Magister]

It stopped doing it, magically, around May 2023, after an automatic upgrade/reboot of my XB7 that happened at 3 or 4AM, I have not touch anything since. Clearly as all my ports were going down, it was the XB7 dropping them, I guess most people use wifi and not ethernet ports, so ISP is not well aware of the problem. Your prob seems DHCP related though.