Archer C7 AP mode suddenly stops working

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Archer C7 AP mode suddenly stops working

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Archer C7 AP mode suddenly stops working
Archer C7 AP mode suddenly stops working
2024-01-25 06:08:07 - last edited 2024-01-25 06:50:08
Model: Archer C7  
Hardware Version: V4
Firmware Version: 1.0.8 Build 20190411 rel.65590(5553)

My archer C7 router in AP was working perfectly fine, but then it suddenly stopped working overnight.

 

Wifi and lan device cannot connect to the internet.

Doing a tracert shows that the packet arrives at the router then times out. 

But in the diagnostic page in the web ui, tracert works perfectly fine.

Wifi and lan clients can see and ping each other just fine.

 

If I switch the router to bridge mode then it works fine, but I lose access to certain functions that are only available in AP mode.

 

I've tried resetting the router, explicitly configuring the dns to 8.8.8.8 on the router and my computer, cloning MAC address from PC, turned off all non-essential features (port forwarding,firewall vpn..etc), the issue still persists.

 

I'm sure all my cables works fine, the wall jack works fine too, I'm 100%sure the issue is the router.

 

What is the problem, how can I resolve it? 

 

Tracert to youtube on router: (the C7 is behind another router, simply because I need internet. The first router is not blocking the C7 in anyway. Making the C7 the first router doesn't change anything,)

 

Tracer to youtube on PC

 

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#1
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Re:Archer C7 AP mode suddenly stops working
2024-01-25 08:23:46 - last edited 2024-01-25 08:25:34

  @Victorlin 

 

You're using C7 in router mode:

 

 

thus introducing a double NAT in your network. That's the reason it's working straighforward when you switch to AP mode.

 

Can you post a screenshot of your C7 Internet settings:

 

 

And also its DHCP server settings:

 

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Re:Archer C7 AP mode suddenly stops working
2024-01-26 07:04:07

  @terziyski Yes sorry, I mean to say router mode is not working and only AP mode works.
I don't think it's an issue with double NAT, cause even when I remove the first router, so that the C7 is connected directly to the ISP, it still doesn't work.

Here are my settings (when connected directly to the ISP, I'm sure the IP and gateway is correct, cause it works on the other router, the MAC is cloning the other router, not that it matters, since it doesn't work even when not cloning)

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Re:Archer C7 AP mode suddenly stops working
2024-01-26 07:43:35 - last edited 2024-01-26 11:27:59

  @Victorlin 

 

I was hoping to see these when you use your main router and the C7 is behind (double NAT scenario).

Remove all optional settings and test connectivity from your PC before switching to the other topology:

 

 

You have a DNS issue on the clients connected to the C7 as can be seen from the tracert www.youtube.com in cmd, but not on the C7 itself.

After switching the configuration execute these commands in your PC cmd (when connected to C7):

 

 

and the result of ipconfig/all of your PC network card:

 

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Re:Archer C7 AP mode suddenly stops working
2024-01-26 11:26:51 - last edited 2024-01-26 11:30:04

  @terziyski here it is when behind the other router, all settings are defaulted after a factory reset, only configured dns.

 

What would the problem be for the clients? I've tried explicitly setting the dns to 8.8.8.8 and 1.1.1.1 on the clients, and it still didn't have internet connection.
Without change anything on my clients, connecting to the other router works just fine, so i highly doubt it's the client. (tested this on 3 different clients, laptop (wifi), desktop (lan), android (wifi))

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Re:Archer C7 AP mode suddenly stops working
2024-01-26 11:34:10 - last edited 2024-01-26 11:36:00

  @Victorlin 

 

No, that's not from your client devices settings. It's from C7 for sure, but no sure yet if that's from its DHCP settings or something else.

I've just edited my post - get rid of the optional settings in C7 DHCP server section as I posted and provide the requested outputs.

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#6
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Re:Archer C7 AP mode suddenly stops working
2024-01-26 11:45:01 - last edited 2024-01-26 11:45:56

  @terziyski Here's the nslookup and ipconfig/all after removing all the optional dns config from dhcp, this all looks like it's working, but still no internet connection

 

.

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#7
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Re:Archer C7 AP mode suddenly stops working
2024-01-26 12:02:25 - last edited 2024-01-26 12:02:54

  @Victorlin 

 

Can you start a tracert www.youtube.com from PC cmd to check the result ?

I can't see your default gateway in the screenshot:

 

 

Did you remove it or it's just not there ?

What DNS servers are on your main router ? Your ISP DNS or different ?

 

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Re:Archer C7 AP mode suddenly stops working
2024-01-29 04:39:19

  @terziyski the default gateway wasn't their for some reason, now it's showing up, and dns seems to work? but no internet connection
the dns on the first router is Primary: 8.8.8.8, Secondary:1.1.1.1

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#9
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Re:Archer C7 AP mode suddenly stops working
2024-01-29 09:41:19 - last edited 2024-01-29 11:04:11

  @Victorlin 

 

That's really wierd. Can you post the C7 routing table:

 

 

Do you have any other network devices in your LAN except the IPS router and Archer C7 ?

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Re:Archer C7 AP mode suddenly stops working
2024-01-29 10:54:55 - last edited 2024-01-29 10:56:16

  @terziyski 
Didn't make any changes to the routing, should be just defaults. 

On my network there used to be some IOT/Smart home was connected to the C7, but after it stopped working, i've moved them to a completely seperate network.
This is what my current network looks like, other than the two routers and my laptop, there's only a Raspberry Pi, that uses the network to get time from the internet over NTP
I have tested unpluggin the Pi from the LAN, doesn't make a difference

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#11
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