Random WAN disconnects

Installing and Using OpenWrt
1

Morning all,

#whoami: Old nerd, 54, Reg’d Linux User #247167 (since 1995), network and network security, homelabber, etc. More: https://www.gofferje.net/

I just moved to a BPI R4 with OpenWRT after my old Cisco ASA at home died a few months ago. I ran into an issue that puzzles me a bit:

Every so and so many days (haven't figured out a pattern yet), my router stops talking to the WAN. When I restart the interface (cli ifdown/ifup or Luci - network - interfaces - restart), everything works fine again. Logs show nothing that seems to be related.

Hardware: Bananapi BPI-R4
OS: OpenWrt SNAPSHOT r28056-40b8fbaa97 / LuCI Master 24.315.52043~d650688

Setup:
Telia Finland Cable -- EuroDOCSIS 3 -- Technicolor CGA2121 (bridge mode) -- GbE -- BPI R4 WAN

Config:

config device
        option name 'br-wan'
        option type 'bridge'
        list ports 'wan'
        list ports 'eth2'

config device
        option name 'wan'
        option macaddr 'ea:de:20:33:ec:0d'

config device
        option name 'eth2'
        option macaddr 'ea:de:20:33:ec:0d'

config interface 'wan'
        option device 'br-wan'
        option proto 'dhcp'
        option peerdns '0'
        list dns '127.0.0.1'
        list dns_search 'gofferje.net'
        option delegate '0'

config interface 'modem'
        option proto 'static'
        option device 'br-wan'
        option ipaddr '192.168.100.2'
        option netmask '255.255.255.0'
        option gateway '192.168.100.1'
        option defaultroute '0'

Any ideas anyone?

2

it's pretty easy to detect an outage by using hotplug or a ping script, and do an ifdown + ifup when it happens.

3

Yes, I'm doing that. It doesn't solve the underlying problem, though. Plus restarting the interface causes a change in public IP which leads to an update of a whole bunch of DNS records which have to propagate through the system. Same for a whole bunch of VPN tunnels. That means outages in the range of minutes which causes my monitoring to pile up a whole bunch of alarms which then fill my mailbox and matrix client, etc. etc. etc.

4

I know, but you said there's nothing usable in the system logs, so it's pretty hard to diagnose your issue ...

assuming it's not a cable issue, can you can you still ping your default gw ?
does the connection die at your location, or further down the line...

5

Jep. If it was easy I wouldn't have to register in the forums to ask for help :stuck_out_tongue_winking_eye:

6

gee, I thought you joined because of our charming personalities :frowning:

1 Like
7

Mh, good point. You just reminded me to check the modem logs and how about that:

11/14/2024 23:46	D3.1	Critical (3)	DHCP FAILED - Critical field invalid in response ;CM-MAC=08:a7:c0:63:33:ac;CMTS-MAC=cc:46:d6:a7:ef:8f;CM-QOS=1.0;CM-VER=3.0;
11/14/2024 23:46	D1.0	Critical (3)	DHCP FAILED - Discover sent, no offer received;CM-MAC=08:a7:c0:63:33:ac;CMTS-MAC=cc:46:d6:a7:ef:8f;CM-QOS=1.0;CM-VER=3.0;
11/14/2024 23:46	D3.1	Critical (3)	DHCP FAILED - Critical field invalid in response ;CM-MAC=08:a7:c0:63:33:ac;CMTS-MAC=cc:46:d6:a7:ef:8f;CM-QOS=1.0;CM-VER=3.0;
11/14/2024 23:46	D1.0	Critical (3)	DHCP FAILED - Discover sent, no offer received;CM-MAC=08:a7:c0:63:33:ac;CMTS-MAC=cc:46:d6:a7:ef:8f;CM-QOS=1.0;CM-VER=3.0;
11/14/2024 23:46	D3.1	Critical (3)	DHCP FAILED - Critical field invalid in response ;CM-MAC=08:a7:c0:63:33:ac;CMTS-MAC=cc:46:d6:a7:ef:8f;CM-QOS=1.0;CM-VER=3.0;
11/14/2024 23:47	D1.0	Critical (3)	DHCP FAILED - Discover sent, no offer received;CM-MAC=08:a7:c0:63:33:ac;CMTS-MAC=cc:46:d6:a7:ef:8f;CM-QOS=1.0;CM-VER=3.0;

Exactly 2 hours later, the connection goes down. Or exactly at this time if the modem time is UTC.

That's new! I don't know that much about DOCSIS but I suppose the modem forwards DHCP requests to it's provisioning server.
The ASA certainly didn't have that problem.
And why the random day intervals? The ISP leases are valid for 8 hours...

Haha, sorry. I tend to be a little sarcastic at times but it's never meant in a bad way.

8

I would talk to the ISP.

as a temp workaround, I'd get a timer that reboots the modem in the middle of the night, as often as needed.

yes, your IP will be renewed and all that, but hopefully the issues related to the reboot and IP change will have fixed themselves by the morning.

can't do much about the alerts you're getting though ... :frowning:

don't worry about the sarcasms, it's my weapon of choice too :slight_smile:

9

Yeah, gotta try that... [rant]But Telia has about the worst service in the world. It's practically impossible to get through to anybody who knows anything about network stuff. The first-liners are trying to bounce off your request as hard as possible... "Have you restarted your modem?", "Oh, your modem is pretty old already, I can connect you to sales","Well, I can send someone but if the fault is in your equipment it's going to cost 100€/h"... ... ... [/rant]

10

get technical, so it goes over their head.

every stupid suggestion they make, tell them you've already done it, multiple times.

I got Telia too, only as the fiber owner though, using a 3rd party for the actual connection.
until the fiber breaks (yes it happens, they're strung up on old telephone poles), I don't have to deal with them.