RT-AC88U dns/dhcp problem?

[ss911der]

Hello,

I have an environment where I have around 30 devices connected at times, mostly wireless, but a few devices are wired into the router, such as a Windows 2016 Server, which acts as a file server and RDP server. The router is a new Asus RT-AC88U.

I'm encountering a strange issue that seems to only affect some devices, but at different times...

For example, I have a HP MFP M477fdw which some computers will lose connectivity to every now and then. If I do a constant ping to the printer, sometimes it will say destination host unreachable, but then after a while it will respond.

If I do the same ping from the server to the printer, it always responds.

I can have two computers both ping the printer at the same time, sometimes one computer will show a response while the other shows destination host unreachable, but after a while they both can ping it fine. It's one of those inconsistent issues that is driving me nuts!

All devices are using the router for dns, 192.168.1.1

The Windows 2016 server has the router in the DNS forwarding config.

There are no special settings, such as firewall rules, routing paths, etc.

This happens with 2 other printers on the network as well...

I've tried things such as turning off ipv6 on the router, disabling roaming assistant, and some other options. The router has the latest Merlin Firmware.

Thanks for any help!

 

[ColinTaylor]

Does this only happen with wireless connections? Is the printer wired or wireless?

 

[ss911der]

The printer is wireless. AP Isolation is off. Server can ping the printer consistently, but both a wired and wireless computer get varied results, sometimes they both can ping, other times maybe one of them can ping, and despite not being able to ping at times, I can load different configuration pages of the printer (http://192.168.1.248) from the server, so it does seem to always be "connected".
192.168.1.94 in this case is the computer doing the pinging.

I have the server and another computer pinging it at the same time, and no lost packets for the last 5 minutes.

The computer with the below results is wired into the router while the other computer and printer I am pinging are wireless.

Pinging 192.168.1.248 with 32 bytes of data:

Reply from 192.168.1.94: Destination host unreachable.

Reply from 192.168.1.94: Destination host unreachable.

Reply from 192.168.1.94: Destination host unreachable.

Reply from 192.168.1.248: bytes=32 time=1190ms TTL=255

Reply from 192.168.1.248: bytes=32 time=7ms TTL=255

Reply from 192.168.1.248: bytes=32 time=14ms TTL=255

Reply from 192.168.1.248: bytes=32 time=22ms TTL=255

Reply from 192.168.1.248: bytes=32 time=6ms TTL=255

Reply from 192.168.1.248: bytes=32 time=4ms TTL=255

Reply from 192.168.1.248: bytes=32 time=8ms TTL=255

Reply from 192.168.1.248: bytes=32 time=2ms TTL=255

Reply from 192.168.1.248: bytes=32 time=5ms TTL=255

Reply from 192.168.1.248: bytes=32 time=2ms TTL=255

Reply from 192.168.1.248: bytes=32 time=4ms TTL=255

 

[agilani]

reserve the first 30 or so ip addresses and remove them from your dhcp scope
assign addresses you excluded from the dhcp scope to the devices manually

or assign static dhcp reservations for the mac addresses of the printers

sounds like wireless interference though

have you checked the arp table when it can't ping to make sure there is an entry in the device doing the pinging for the mac/ip address combination?

 

[ss911der]

But if it was wireless interference, wouldn't I not always be able to access/ping from the server? I tried giving it a static as well. I also changed wireless channels from auto to 11 after I found it to be the least used from nearby ssid's. I turned off roaming assistant as well...
I did also think it was a wireless issue at first until I was able to consistently access it from the server...

 

[ColinTaylor]

Maybe it's just wireless congestion on the access point. ICMP packets will be dropped in preference for other packets if there's not enough "free air time". Do you think it's connected to how much traffic is going through the access point?

 

[ss911der]

There's nobody in the office right now, so that should not be the case. I only have about a dozen devices connected at the moment, where normally there would be close to 30. Wouldnt ICMP packets be dropped regardless of whether I am pinging from the wired server vs a wireless computer? I can run a ping -t 192.168.1.248 from the server and never lose the packet while at the same time ping from the other workstations and have trouble communicating. The wireless clients have a strong signal, and I am losing pings from another wired workstation which throws off a lot of my theories...

 

[agilani]

But if it was wireless interference, wouldn't I not always be able to access/ping from the server? I tried giving it a static as well. I also changed wireless channels from auto to 11 after I found it to be the least used from nearby ssid's. I turned off roaming assistant as well...
I did also think it was a wireless issue at first until I was able to consistently access it from the server...

take a look at the wireless log and see what the device is connecting as and take a look and see which wireless device is losing is connection. maybe post a screen capture of the wireless logs for us to eyeball.

the device that does not lose packets is wired? airtime fairness is turned off? what band are the devices connected to?

run two continuous pings - one to the printer, the other to the router - see if the packet get dropped at the same time.

are the devices going into powersave mode? can you do a wireshark on the device with the packets getting dropped and see if its arping for the mac address?

 

[ColinTaylor]

Sounds like it's not the printer then. I think you'll just have to try and see if the problem clients have something in common. 2.4GHz vs. 5GHz? MacBook's vs. Dell's etc.

 

[ss911der]

Printer is using 2.4 Ghz, and router is set for 20/40 Mhz. Wireless client is also connected to 2.4 Ghz. Yes, I am testing with two wired computers (one 2016 server, one windows 7 machine), and one wireless windows 7 station.
I left the server pinging for a while, here are the results:
Ping statistics for 192.168.1.248:
Packets: Sent = 11221, Received = 11220, Lost = 1 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 1ms, Maximum = 111ms, Average = 3ms

 

[ss911der]

Aug 11 13:08:27 kernel: Register interface [eth2] MAC: removed for privacy
Aug 11 13:08:36 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:08:41 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:08:41 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:08:41 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:08:41 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:08:41 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:08:51 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:08:56 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:08:56 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:08:56 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:08:56 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:09:11 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:10:01 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:17:16 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:22:56 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 13:53:06 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 14:09:10 miniupnpd[14377]: upnp_event_recv: recv(): Connection reset by peer
Aug 11 14:09:10 miniupnpd[14377]: upnpevents_processfds: 0x2b198, remove subscriber uuid:bff5a0ce-3b9f-4d99-88cc-e22b25479b34 after an ERROR cb: http://192.168.1.206:2869/upnp/eventing/lukekznpdr
Aug 11 15:13:36 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 15:45:26 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 16:30:06 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 17:15:37 dnsmasq-dhcp[2590]: Ignoring domain removed for privacy for DHCP host name removed for privacy
Aug 11 18:09:27 rc_service: httpd 2681:notify_rc restart_wireless
Aug 11 18:09:29 kernel: dhd_detach(): thread:dhd_watchdog_thread:5310 terminated OK
Aug 11 18:09:29 kernel: dhd_detach(): thread:dhd_watchdog_thread:530c terminated OK
Aug 11 18:09:33 kernel: PCI_PROBE: bus 1, slot 0,vendor 14E4, device 4365(good PCI location)
Aug 11 18:09:33 kernel: dhd_attach(): thread:dhd_watchdog_thread:707e started
Aug 11 18:09:33 kernel: Dongle Host Driver, version 1.363.2 (r665954)
Aug 11 18:09:33 kernel: Compiled in drivers/net/wireless/bcmdhd on Jun 20 2018 at 12:12:56
Aug 11 18:09:33 kernel: Register interface [eth1] MAC: removed for privacy
Aug 11 18:09:33 kernel: PCI_PROBE: bus 1, slot 0,vendor 14E4, device 4365(good PCI location)
Aug 11 18:09:34 kernel: dhd_attach(): thread:dhd_watchdog_thread:7082 started
Aug 11 18:09:34 kernel: Dongle Host Driver, version 1.363.2 (r665954)
Aug 11 18:09:34 kernel: Compiled in drivers/net/wireless/bcmdhd on Jun 20 2018 at 12:12:56
Aug 11 18:09:34 kernel: Register interface [eth2] MAC: removed for privacy
Aug 11 18:09:43 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 18:09:49 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 18:09:49 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 18:09:49 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 18:09:49 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 18:09:49 roamast: eth2: add client [removed for privacy] to monitor list
Aug 11 18:10:20 rc_service: cfg_server 28962:notify_rc restart_wireless
Aug 11 18:10:21 kernel: dhd_detach(): thread:dhd_watchdog_thread:7082 terminated OK
Aug 11 18:10:21 kernel: dhd_detach(): thread:dhd_watchdog_thread:707e terminated OK
Aug 11 18:10:25 kernel: PCI_PROBE: bus 1, slot 0,vendor 14E4, device 4365(good PCI location)
Aug 11 18:10:25 kernel: dhd_attach(): thread:dhd_watchdog_thread:7174 started
Aug 11 18:10:26 kernel: Dongle Host Driver, version 1.363.2 (r665954)
Aug 11 18:10:26 kernel: Compiled in drivers/net/wireless/bcmdhd on Jun 20 2018 at 12:12:56
Aug 11 18:10:26 kernel: Register interface [eth1] MAC: removed for privacy
Aug 11 18:10:26 kernel: PCI_PROBE: bus 1, slot 0,vendor 14E4, device 4365(good PCI location)
Aug 11 18:10:26 kernel: dhd_attach(): thread:dhd_watchdog_thread:7178 started
Aug 11 18:10:27 kernel: Dongle Host Driver, version 1.363.2 (r665954)
Aug 11 18:10:27 kernel: Compiled in drivers/net/wireless/bcmdhd on Jun 20 2018 at 12:12:56
Aug 11 18:10:27 kernel: Register interface [eth2] MAC: removed for privacy
Aug 11 19:23:35 rc_service: httpd 2681:notify_rc restart_dnsmasq
Aug 11 19:23:36 dnsmasq[32119]: warning: no upstream servers configured

 

[HowIFix]

Maybe some USB3 creates interference 2.4G devices like this:

Finally figured it out, connecting anything USB3 to the Shield TV creates massive interference on all 2.4G devices BT and WiFi. Even with shielded extension cables and ferrite cores it was unusable.

Try this:

Hi telUK,

These are my settings under Wireless and Professional.

5GHz

Control channel: 44 (manually set)
Channel bandwidth: 20/40/80 mhz

Under Professional settings:

Airtime fairness: disabled (disabled by default in Merlin)
Universal beamforming: disabled (leave 802.11ac Beamforming enabled)

2.4GHz

Control channel: 6 (manually set)
Channel bandwidth: 20mhz (manually set)

Under Professional settings:

Turbo QAM: disabled
Airtime fairness: disabled (disabled by default in Merlin)
Beamforming settings: disabled (both)

It enables higher non-standard modulation speed QAM-256 (MCS8/9), few clients support it and only nearby router, usually could only cause troubles.
Similar to QAM-1024 (MCS10/11) in 5G.

 

[ss911der]

Um, wrong thread?

 

[ss911der]

I don't believe interference is a factor in my situation, otherwise I wouldn't be able to consistently ping the wireless printer from the wired server while the wired computer next to the server is inconsistent...

 

[HowIFix]

and why do not you try that, to be sure it's not interference or some wireless setting.

 

[ss911der]

Does this look ok? I rather not turn anything off that isn't necessary that could sacrifice performance.

 

[agilani]

it could be wireless interference on the devices that are doing the pinging

you shared the ping from the server, what about the workstation that is losing packets? And from the same workstation to the default gw.

you screenshot is blurry, but it looks like the wireless signal to the printer is ok. It looks to be an older device that only supports g speeds. Which wireless device is losing the packets form this list?

 

[ss911der]

After making some suggested changes as can be seen with the posted screenshot of the wireless professional tab, the wired and wireless workstations are able to ping the server without any "Destination host unreachable." messages. I had my doubts that interference was causing what I was experiencing, but at the moment, I am shocked. So it's possible it's a bluetooth and/or USB 3 device was causing this?!
I'll try the pings a few more times over the next day or so as this issue has been so inconsistent and i've been pulling my hair out trying to narrow it down. Thanks!

 

[ss911der]

If I find out it's one of the user's bluetooth speakers that she uses to play music, I am going to smash it into tiny little bits! Hours wasted!!!