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Possible DNS and/or DHCP issue?


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,

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!

Also posted in TechSupport:

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level 1
higher ed cisco aruba nac 5 points · 8 days ago

Can we say "don't use a home router for business purposes" on this one?

It's not a DNS thing. You're not trying to ping a domain name.

It's not DHCP, your stuff has addresses.

It could be crappy cabling.

Corollary to the above: it COULD be DHCP, if you have machines that are NOT set to DHCP that could be using the same address as another device.

Check your ARP cache and see what devices have which IPs. I'm smelling duplicate IPs.

Edit: 'destination host unreachable' can also be the concept that the machine you're pinging from literally isn't connected, and has no route to the host. check your wiring.

level 1
Original Poster1 point · 8 days ago 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 with 32 bytes of data:

Reply from Destination host unreachable.

Reply from Destination host unreachable.

Reply from Destination host unreachable.

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

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

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

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

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

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

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

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

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

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

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

level 2

If you are pinging by address ("ping") it isn't likely to be DNS. Or are you pinging by name ("ping hpthing")?

level 3
Original Poster1 point · 8 days ago

Thanks for the reply... it appears that interference from possibly a bluetooth speaker is what is causing all the chaos. A user in snbforums suggested turning off beamforming and airtime fairness and so far things appear to be ok. I am about smash a users bluetooth speaker! So many hours spent doing a process of elimination!

level 1
1 point · 8 days ago


level 2
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