Cisco RV340-router44808B wan interface continuously down and up

[nath1]

Hi. I have a Cisco RV340 router configured straightforward with one WAN interface linking to my ISP. The Cisco-router is running the latest firmware version (Version 1.0.03.22). About 4-5 times a day the wan interface goes down and we are offline for about 2-3 minutes until the interface is back up again. I have tried to debug and check the log files, but I simply cannot understand what is going on. To fix the problem I have forced the Mode to "100Mbps Full" on my side and the ISP has done that as well, but that did not solve the problem. Can someone come up with any ideas as to what could be going on? I have attacched the log output from one of the incidents (it happens 2021-09-30T08:23:20+01:00, line 1199 in the log file)

[marce1000]

                                                                - Check the wan-interface counters :

           https://www.cisco.com/c/en/us/support/docs/smb/routers/cisco-rv-series-small-business-routers/smb5497-view-the-port-traffic-statistics-on-the-rv34x-series-router.html

            Whatever equipment is involved at the other end the ISP-provider should likewise examine  link-integrity accordingly.

 M.

[Georg Pauwen]

Hello,

could be the firewall on your router. What settings are you using, the default ?

[nath1]

Hi Georg

Yes I am using the default settings. I have never changed anything in that section of the admin settings.

Br

[nagrajk1969 · Accepted solution]

Hi

You have configured wan1 interface for the internet connection thru the isp-router

- (from the logs) You wan ipaddress is 77.243.43.178 as of now

- so iam assuming for sake of example that the default-gateway configured on the wan1 interface is 77.243.43.1

So what's happening mostly as per my opinion/understanding is:

1. In the GUI, under WAN/MultiWAN if you edit the "wan1" interface you will see the "Network Service Detection" feature settings

2. Now this MultiWAN service/feature (including the Network Service Detection) is what controls the "Failover-Mode" and "Load-Balancing Mode" functions of this Dual-WAN Router

a) and in this aspect, by default the Network-Service-Detection is enabled on wan1 (and wan2) interface and the default setting is to "Default Gateway/Default-Route" configured on the wan1 interface

b) and what this multiwan-NSD does is to send pings at regular intervals (as per the default settings) to the configured default-gw (77.243.43.1) and wait to recieve ping replies to the pings-sent

c) And if the ping-replies are not recieved (becos the isp-router does not respond or does not respond quickly enough for some reason within the timeouts set in NSD config page for wan1), then the "MultiWAN" service running on the RV34X router will simply make the wan1 interface "offline" and stop routing traffic over this wan1 link....(and if wan2 is active, then it will also automatically route all traffic via the wan2 internet link)

- but at regular intervals, eventhough wan1 is "offline" (and not down per se) it will continue to attempt the ping-keepalives to the default-gateway ip...AND if it recieves the ping replies as expected...it will then once again make the wan1 interface "Online" and start routing traffic thru this primary wan1 link to internet

3. So check in the NSD config page (as show in attachment sample screenshot) and you decide either of the 2 settings below:

a) If you have ONLY 1 wan1 link, then i would strongly (highly recommend) that you should DISABLE NSD on wan1 and apply and do a permanent save AND REBOOT THE RV340 ONCE

b) And only if and when you have a secondary internet link on wan2, then i suggest you should instead of using the default-setting of NSD (to Default-Gw), configure the google DNS-srver ipaddr 8.8.8.8 for the tracking/keepalive.....

i think this should solve your issue of connection going down often

thanks

[nath1]

Hi @nagrajk1969 

This seems like a very possible explanation! I will deactivate this right away and monitor the situation.

Thanks!

Br

[nath1]

Thank you @nagrajk1969 . I changed the settings Thursday, and since then the router has performed without any issues at all. This was indeed the root cause. Thanks again!

[nagrajk1969]

Thank you so much. Iam glad that my inputs could be of some help

Best wishes and regards