Cisco RV 340 dropping Xfinity WAN

[OnTheCatwalks]

Good Afternoon,

Got a strange issue I have not been able to solve. I have been using this router unchanged for exactly a year. One morning I get a text from Comcast saying they are updating the network in the area. Later that day I get another text saying it's done. Ever since my Cisco will drop the WAN traffic after about 10 pings. Tried both WAN ports,same issue. Factory reset it...same issue. Enabled and disabled IPv6....same issue. If I disable PnP I get about 20 pings....same thing. All security off and firewall disabled....same thing. Spoofed the MAC of a working device....same issue.. What did Comcast break? I can plug any router or an ASA in and its fine. What am I missing ???

[nagrajk1969 · Accepted solution]

try with

Step-1:disabling "Network Service Detection" setting for both WAN1 & WAN2 interfaces under "WAN\MultiWan" gui page

-and then Apply and permanent-save to startupconfig

Step-2 : just this once reboot the router...and wait for my minimum of 150 secs for the reboot to complete...

- and then check your link status and etc

[matthew]

Thank you that fixed my problem also.  Got a text from comcast they were upgrading my internet after it came back online, my tcp/ip would work (my vpn's would connect over comcast to their destination site) but nothing else would work such as DNS resolution.  Other routers such as asus would work.  Once I applied the above change now my rv345 is working great again on comcast.  At this site I only have one wan port configured however at my other site I have comcast and at&t configured in a failover situation so I am concerned if this "upgrade" is rolled to my other site that it would break wan failover.  We shall see.

[Robert4342]

This fixed my issue too.  The description exactly matches my experience.  I went months with xfinity's gateway because I thought my old modem was the fault.  Saw the new modem with this issue and googled "rv340 xfinity no internet" and found this.  Thank you so much.

[OnTheCatwalks]

Thank You!!! That did the trick.

[jacunningham423]

I gave up on several RV345Ps and RV340s back in the summer of 2021 over this issue.  Exact same scenario and failure--other routers worked fine with the modem and the RV-series units worked fine with any other WAN.

Still have a few of these floating around and had another one (running .29 firmware) start this yesterday after comcast work in the area.  The dynamic wan IP jumped to a different subnet after the work and icmp is now disabled on the subnet gateway--I can only assume that's the mechanism Cisco is using here for the gateway monitor.

This is a flaw/bug in my opinion.  Failure of a monitor on a device that is not configured for WAN failover should not stop traffic on the interface.  Even more perplexing is that the ipsec tunnels all continued to function.

Thank you for posting.