Internet periodically goes down

Installing and Using OpenWrt
1

Hi,

Have recently migrated to NowTV (UK) and I am seeing an issue where occasionally Internet goes down. The wan interface keeps its IP address but anything on the Internet isn't reachable anymore (including the ISP's gateway). Everything starts working as soon as I issue a ifup wan on the command-line (as a workaround I have added that to the system crontab) at which point the lease and IP are renewed.

Running OpenWRT snapshot r21950-90dbdb4941 on a R6260 plugged into a HG612 in its default configuration.

Snipped contents of /etc/config/network as according to the wiki page here follows. I am not using IPv6.

config interface 'wan'
        option device 'wan'
        option proto 'dhcp'
        option delegate '0'
        option hostname '*'
        option clientid '33643966633733376530323940736b7964736c7c3132333435363738'
        option macaddr '3D:9F:C7:37:E0:29'

Not 100% sure that when this happens this matches the DHCP lease time which is set to 3600s and I am not seeing anything relevant when that happens with logread either:

# ifstatus wan|grep leasetime
                "leasetime": 3600
# logread|grep udhcpc
Mon Feb  6 17:10:26 2023 daemon.notice netifd: wan (4887): udhcpc: sending renew to server xxx.xxx.xxx.xxx
Mon Feb  6 17:10:26 2023 daemon.notice netifd: wan (4887): udhcpc: lease of xxx.xxx.xxx.xxx obtained from xxx.xxx.xxx.xxx, lease time 3600

Thanks in advance!

2

Looks like your ISP interrupts your WAN connection in order to assign a new IP address for you.

In the past I had the same problem with Vodafone and O2 in Germany: Vodafone cuts the connection 72 hours at the latest, O2 24 hours at the latest.

Are your down times random or regular?

3

I think that they were all mostly regular and might have matched a time the lease was being checked and probably renewed although it seemed to happen randomly on a couple of occasions but it could have been an unrelated transient issue.

Have you done anything on your side to circumvent that besides the ifup crontab workaround?

4

No, because of my hardware situation.

I connect to the internet via LTE with a Zyxel LTE4506 router. This device operates in bridge mode and therefore is just a LTE modem.

The Zyxel's LAN port is connected via cable with the WAN port of my OWRT router (rpi4, nanopi r1 or zeropi). Because those devices have only 1 ethernet port I use a TP-Link UE300 USB-ethernet adapter as WAN port (driver rtl8152).

When the ISP assigns a new IP address for the LTE4506, the LAN port changes to "link down" state and again to "link up" state, when the new address is assigned.

The OWRT router reacts to the "link down" state with a "ifdown wan" call. When "link up" state is entered OWRT calls "ifup wan" to get the new address from the LTE4506. This behaviour may be driver specific. Therefore I don't need a "ifup wan" call via crontab.

The down time from loosing the old address till getting a new address is less than 60 seconds with Vodafone, less than 90 seconds with O2.

If you have any further questions, don't hesitate to ask.