[SOLVED] Wireless Access Point mode suddenly broken

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jeffmakes
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PostPosted: Wed Aug 10, 2022 19:01    Post subject: [SOLVED] Wireless Access Point mode suddenly broken Reply with quote
Hi,

I have a Netgear R7000P operating in WAP mode, to extend the coverage of a wifi network served by another router supplied by my ISP - a BT Homehub. The Homehub works as the modem and router, and connects to the R7000P by an ethernet cable. Some devices connect to the R7000P via wifi and ethernet. The SSID is the same for both router and AP to allow roaming.

I followed https://wiki.dd-wrt.com/wiki/index.php/Linking_Routers and, more specifically, https://wiki.dd-wrt.com/wiki/index.php/Wireless_access_point to configure the R7000P.

This has been working perfectly for several months, until yesterday when the R7000P suddenly stopped routing traffic. I rebooted it a few times, no effect. I logged in and updated the firmware to 49677 via the web interface. I reconfigured it per the guide, no improvement.

I then performed a hard reset by pressing the reset button for 30 seconds. Reconfigured again per the guide, no improvement.

When I perform a hard reset, my PC can connect to the dd-wrt wifi network and reconfigure the router, but once configured and rebooted, the PC can't connect to the R7000P's wifi network, whether I have changed the SSID to match the Homehub or not, presumably because the R7000P isn't forwarding my PC's DHCP request through to the Homehub. It sits, trying to connect, for a couple of minutes then times out.

Meanwhile, the Homehub is working fine - I can connect to its wifi network and it routes traffic to the internet. I can't ping the R7000P from the Homehub network.

It's almost as if the R7000P's ethernet ports have randomly blown up. The LED for Port 1 - the ethernet connection to the Homehub - blinks briefly roughly once per second.

Has anyone seen this behaviour before?
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kernel-panic69
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PostPosted: Wed Aug 10, 2022 19:38    Post subject: Reply with quote
A 30-second reset may put the router in TFTP recovery mode and is not advised on Broadcom ARM Northstar routers. Should only require a ~10 second reset button push. WAP mode doesn't require DHCP forwarder, so if you configured that, change it to disable DHCP altogether in DD-WRT as well as disabling DNSMasq on the services page. The LEDs do not flash rapidly that I recall. Fast transition / roaming may not work all that well on Broadcom to begin with, and some clients may not play well with it, either. Client OSes involved and config details may help us sort this out, or not.
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jeffmakes
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PostPosted: Thu Aug 11, 2022 22:38    Post subject: Reply with quote
Thanks for the reply!

The clients are a Linux laptop (Fedora 36) and an Android phone (Samsung Galaxy Fold 2). Both work fine on the BT Homehub wifi network. Apologies for the confusing language - I'm not using DHCP forwarding.

Here are my settings:







https://imgur.com/a/94TJNIO

I've tried to follow the wiki guide to the letter - can you spot any mistakes?
kernel-panic69
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PostPosted: Thu Aug 11, 2022 23:24    Post subject: Reply with quote
You have dhcp server disabled, but dhcp authoritative checkbox marked (uncheck that, save)

For wl0 (2.4):
NG-Mixed, Ack Timing 900 or 1350

For wl1 (5GHz):
AC/N-Mixed,
select a channel width, save;
select extension channel, save;
pick a channel, save.
Auto channel is not recommended.
Ack Timing 900 or 1350.

For the firewall, check nvram via telnet / ssh: nvram show | grep block_multicast. If it's 0, do an nvram set block_multicast=1 && nvram commit && reboot.

On the Services -> Services tab, I would enable syslogd and klogd, save. I would also switch from using telnet to using sshd, mainly due to security or lack thereof in telnet.

Of course, it goes without saying, reboot after you've made these changes. I didn't see wireless advanced pages, so no clue what you have there.

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egc
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PostPosted: Fri Aug 12, 2022 9:28    Post subject: Reply with quote
Your router suddenly stopped working while you did not changed anything right?

Those things happen but a simple reboot (switch on and off) should usually get it in working state.

If not I would not rule out a hardware failure, the easiest thing to test is another power supply if you have one I would replace it to test

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kernel-panic69
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PostPosted: Fri Aug 12, 2022 12:39    Post subject: Reply with quote
I sometimes have to cycle wifi on Android for it to reconnect to my AP (TL-WA901ND v2). Fedora is RedHat, and it probably still has all of the nuances of pre-RHEL that I'm not fond of all the way back to Biltmore (4.2). Forget network and reconnect on both. Sorry for not addressing that bit sooner in the thread.
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jeffmakes
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PostPosted: Fri Aug 12, 2022 14:04    Post subject: Reply with quote
egc wrote:
Your router suddenly stopped working while you did not changed anything right?

If not I would not rule out a hardware failure, the easiest thing to test is another power supply if you have one I would replace it to test


Thanks for the input. That's right - it suddenly stopped routing any traffic (via ethernet) to the main router.

I don't think it's a PSU issue because it boots up fine, its wifi network works, and I can log in and configure it for WAP mode via the web interface, etc. Once configured, I can connect to it via wifi (only if I assign myself a static IP, because DHCP is disabled by that point), but it won't route traffic to the main router.

If it is a hardware issue, I think the only problem could be its ethernet ports. I'll test them and report back.
jeffmakes
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Joined: 03 Aug 2020
Posts: 9

PostPosted: Fri Aug 12, 2022 14:06    Post subject: Reply with quote
kernel-panic69 wrote:
I sometimes have to cycle wifi on Android for it to reconnect to my AP (TL-WA901ND v2). Fedora is RedHat, and it probably still has all of the nuances of pre-RHEL that I'm not fond of all the way back to Biltmore (4.2). Forget network and reconnect on both. Sorry for not addressing that bit sooner in the thread.


Thanks, yes, I've done plenty of forgetting, reconnecting and restarting of the Network Manager service. I even resorted to a reboot!

I'll try the extra configuration steps you suggested in your previous message and report back.
jeffmakes
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PostPosted: Fri Aug 12, 2022 14:50    Post subject: Reply with quote
Ok, I've added the extra settings, following your suggestions. I checked the block_multicast flag, it was already set. Rebooted, ofc.

I've connected my laptop to the R7000P via ethernet. I get a DHCP lease (presumably from the Homehub, since DHCP on the R7000P is disabled). On a fresh boot of the R7000P, I can ping both the R7000P and the Homehub when connected only by ethernet (wifi disconnected), and I get an internet connection. So the ethernet hardware appears to work ok.

To reiterate - this is in contrast to connecting via wifi, when traffic never gets routed from the R7000P to the Homehub (and onwards to the internet).

However, it doesn't seem to be stable - If I unplug/plug the ethernet cable to my laptop, it won't get a DHCP lease again, and if I set a static IP, it can't ping the R7000P or the Homehub. The same as the state with wifi - no traffic being routed.

If I then power cycle the R7000P, the ethernet connection works again.
kernel-panic69
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PostPosted: Fri Aug 12, 2022 15:18    Post subject: Reply with quote
Having used an old Macbook with Debian installed, there is a noticeable delay in reconnection via ethernet or wifi, but it should be within a minute (unlike Windows garbage). This could be an issue with the HomeHub or your Fedora client and not DD-WRT, but I have not tested this theory out with my own R7000P in WAP mode. More recently, though, I exprienced an anomaly after doing a non-reset reconfiguration from wireless client on 2.4 to a normal dual-band AP in default gateway mode (double NAT) where clients were getting an IP and internet without fail from the upstream router because the WAN port was still assigned to the common br0 bridge interface (probably because I manually assigned it to test something else). If dnsmasq and dhcp server are both disabled like they should be, there should be no issues here, unless as mentioned elsewhere, setting router mode is unnecessary.
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jeffmakes
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PostPosted: Fri Aug 12, 2022 16:07    Post subject: Reply with quote
Wooooo! Thanks so much kp, I've got it working! I was just about to buy a new router.

I noticed that I somehow hadn't applied some of the wifi settings you had suggested, including the channel settings.

I installed a wifi scanner app on my phone, and noticed that both the 2.4 and 5GHz interfaces were tuned on top of several other stations. With all settings applied and interfaces tuned into empty spectrum the R7000P sprang into action.

Still don't know the origin of the problem - maybe some new wifi network was set up in the neighbourhood and it was clashing with mine... Who knows.

Hopefully I haven't spoken too soon. I'll stress-test it and report back if new problems develop.

Thanks for all the help.
Jeff
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