Asus RT-AC68U - Connected but no Internet on devices upon reconnect. Upgraded to RT-AX86U and having the same problem!

jes1789

New Around Here
We recently got our internet service upgraded (new modem and faster speed). When we did that, I took the time to upgrade the firmware on our RT-AC68U to the latest. The firmware had not been updated since 2018. Ever since then, we are having connectivity issues. The router is getting Internet and the devices that were left on continue to have connectivity. But, turning on computers that were turned off (wired) and bringing in mobile devices from outside (wireless) show as "Connected but no internet" and do not have internet connectivity. To fix the issue, I'm telling people to turn their Wifi on and off a few times, and doing this fixes the issue on just about all mobile devices. On the Windows PC (wired through a switch), I have to perform dhcp renew (ipconfig /release && ipconfig /renew) 2 or 3 times to get internet connectivity. The DVR and computers that have been left on do not lose connectivity at all.
I figured we had an issue with our older router so I upgraded us to the RT-AX86U, but we are experiencing the same exact issues.

I changed the WAN DHCP mode from Aggressive to Normal, but that doesn't seem to have an effect as expected.
Is there some setting specific to Asus routers that it causing this issue? Is their some incompatibility with our ISP?
Any help is greatly appreciated.
 

ColinTaylor

Part of the Furniture
Save the contents of your router's System Log and upload it here or to pastebin.com for us to look at.

Also check the log on the modem for errors.
 
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jes1789

New Around Here
Router log attached. It's been 2 days since last reboot. The modem is a Technicolor TC4400-AM provided by the ISP. The event log on the modem says they are "hidden", but I've included a few screenshots of some of the settings from the Modem UI.
 

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ColinTaylor

Part of the Furniture
Is your Dell PC a fixed desktop or is it a laptop that moves between networks (e.g. work and home). The reason I ask is because it appears that it is connecting to multiple networks. If this is not intentional it would probably indicate that you have another DHCP server running on your LAN.
 

jes1789

New Around Here
The Dell PC is a fixed Desktop that is wired to a 4-port switch that is connected to the router. It may also be configured to connect to the Wifi, I have to double check that. Is it possible that the Dell is switching between Wifi and Ethernet? Or does it look like the cable modem (Technicolor TC4400-AM) is acting as a DHCP server in addition to the Asus router?
 

ColinTaylor

Part of the Furniture
Is it possible that the Dell is switching between Wifi and Ethernet?
It's possible but wouldn't normally cause this sort of issue.

Or does it look like the cable modem (Technicolor TC4400-AM) is acting as a DHCP server in addition to the Asus router?
From what I can find on the internet this is just a simple modem. It will provide DHCP from the ISP to the router's WAN port but this is normal. Provided that the router is the only device connected to the modem there should not be a problem.

Do you have any other network devices on your LAN that might contain a DHCP server, e.g. repeaters, routers, NVR, etc?
 

jes1789

New Around Here
Ahhh we do have an NVR (link XRN-810S). It has 6 Ethernet surveillance cameras. My understanding was that the network that connects to the cameras and the network the connects externally were completely segregated, but maybe that is the whole problem. We have had this NVR for several years and only starting causing issues when we got a new cable modem/upgraded firmware. Would that somehow make sense?
 

ColinTaylor

Part of the Furniture
Ahhh we do have an NVR (link XRN-810S). It has 6 Ethernet surveillance cameras. My understanding was that the network that connects to the cameras and the network the connects externally were completely segregated, but maybe that is the whole problem. We have had this NVR for several years and only starting causing issues when we got a new cable modem/upgraded firmware. Would that somehow make sense?
I don't have any experience myself with NVRs. From what I've read some of them have a separate IP network for IP cameras, which runs it's own DHCP server. The NVR would then have a second network interface that connects to your main LAN, so the two networks are separate. If you were to connect both network interfaces to the same switch it would create problems. Of course if the cameras are just analogue rather than IP this is not an issue.
 

ColinTaylor

Part of the Furniture
EDIT: Looking at the NVR link you provided... make sure the NVR's "WAN" connection is the only one connected to your LAN. The PoE camera ports should be completely isolated from your LAN.
 

jes1789

New Around Here
I don't have any experience myself with NVRs. From what I've read some of them have a separate IP network for IP cameras, which runs it's own DHCP server. The NVR would then have a second network interface that connects to your main LAN, so the two networks are separate. If you were to connect both network interfaces to the same switch it would create problems. Of course if the cameras are just analogue rather than IP this is not an issue.
The cameras are IP (PoE). I'm pretty positive that only the "WAN" connection is wired into our network, but I will go double check later today. I also need to verify that network settings on the WAN port, but I believe they are pretty straightforward.
 

jes1789

New Around Here
EDIT: Looking at the NVR link you provided... make sure the NVR's "WAN" connection is the only one connected to your LAN. The PoE camera ports should be completely isolated from your LAN.
I definitely think this is our problem, so I also plan to reach out to the manufacturer and see if they have suggestions. Thanks so much for you help Colin!
 

ColinTaylor

Part of the Furniture
I definitely think this is our problem, so I also plan to reach out to the manufacturer and see if they have suggestions. Thanks so much for you help Colin!
It ought not to be a problem provided that none of the camera Ethernet connections are cross-connected to your LAN. It should be pretty easy to check if there's something not working right with the NVR, just turn it off and see if your network problems go away.

EDIT: Reading the user manual for the NVR, the WAN port appears to be labelled "Viewer".
 
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jes1789

New Around Here
It ought not to be a problem provided that none of the camera Ethernet connections are cross-connected to your LAN. It should be pretty easy to check if there's something not working right with the NVR, just turn it off and see if your network problems go away.
 

jes1789

New Around Here
So, the WAN cable was the only one wired into the switch, with the other ports all being used by cameras. But....turns out the NVR provides a DHCP server that can enabled/disabled on each respective interface. And it was enabled on the WAN interface as well as the camera interface. I'm not sure how that happened or if it was configured that way since it was installed and just now started causing issues. So, disabled that and all connectivity issues are gone as expected. Thanks so much for digging through the logs and identifying this for us. Appreciated much!
 

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