DHCP problem with RT-AX58U... Or is it?

[knatterton]

I have a very strange problem with the WAN connection of RT-AX58U. First I thought it's an issue with DHCP, since I keep getting messages about ISP's DHCP not working correctly. I'm not convinced this is really about DHCP though. The problem is so strange, I can't really understand it.

Most of the time when I wake my PC from sleep, it causes the WAN connection to go down for maybe 3 or so minutes. While it happens I get the DHCP error message. My PC is using wifi to connect to the router. The router is connected to a VDSL2 modem which is in bridge mode. This problem started right when I bought the new router around a month ago. I used to have RT-N66U and I never had this problem with it. Nothing else has changed. I tried replacing the ethernet cable between my modem and the router, but it didn't help. I have the latest Asuswrt-Merlin installed, but the problem also happened with the original Asus firmware.

I'm attaching a log about the situation. You can see at the start that DHCP renewal was done successfully. Then at 8:37 I turned on my PC. The internet worked okay for a few minutes. Then at 8:42 WAN goes down and this time takes just around one minute until it starts working properly again. I cannot understand the link between turning on my PC and the connection dying, but it has happened a lot of times now and at different times of the day. I don't believe it can be a coincidence. This problem can happen randomly at other times too, but very rarely. Mostly it happens a few minutes after I've turned on my PC. I would really appreciate it if someone could explain to me what's going on. I'm getting a new modem to try next week, but I don't expect it to fix things.


Feb 12 07:30:54 custom_script: Running /jffs/scripts/dhcpc-event (args: renew)
Feb 12 08:30:54 custom_script: Running /jffs/scripts/dhcpc-event (args: renew)
Feb 12 08:37:59 wlceventd: wlceventd_proc_event(505): eth6: Auth 9C:FC:E8:B8:CD:EC, status: Successful (0)
Feb 12 08:37:59 wlceventd: wlceventd_proc_event(534): eth6: Assoc 9C:FC:E8:B8:CD:EC, status: Successful (0)
Feb 12 08:37:59 hostapd: eth6: STA 9c:fc:e8:b8:cd:ec IEEE 802.11: associated
Feb 12 08:37:59 kernel: CFG80211-ERROR) wl_cfg80211_change_station : WLC_SCB_AUTHORIZE sta_flags_mask not set
Feb 12 08:37:59 hostapd: eth6: STA 9c:fc:e8:b8:cd:ec RADIUS: starting accounting session D9FE1E15C258A6A4
Feb 12 08:37:59 hostapd: eth6: STA 9c:fc:e8:b8:cd:ec WPA: pairwise key handshake completed (RSN)
Feb 12 08:37:59 dnsmasq-dhcp[17882]: DHCPREQUEST(br0) 192.168.1.2 9c:fc:e8:b8:cd:ec
Feb 12 08:37:59 dnsmasq-dhcp[17882]: DHCPACK(br0) 192.168.1.2 9c:fc:e8:b8:cd:ec pc
Feb 12 08:42:22 kernel: eth4 (Int switch port: 4) (Logical Port: 4) (phyId: c) Link DOWN.
Feb 12 08:42:24 WAN_Connection: ISP's DHCP did not function properly.
Feb 12 08:42:24 kernel: eth4 (Int switch port: 4) (Logical Port: 4) (phyId: c) Link Up at 100 mbps full duplex
Feb 12 08:42:29 WAN_Connection: WAN(0) link up.

 

[ColinTaylor]

The VDSL modem rebooted itself. Check the logs on the modem.

 

[knatterton]

I received a new VDSL2 modem (Planet VC-231G) and I've been using it for a week. There have been no issues since then, so it seems that the old modem really was the problem.