Press J to jump to the feed. Press question mark to learn the rest of the keyboard shortcuts
0

Possible DNS and/or DHCP issue?

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!

Also posted in TechSupport: http://goedhartvoordieren.nl/?page=r/techsupport/comments/96kx3s/dns_andor_dhcp_issue/

6 comments
38% Upvoted
What are your thoughts? Log in or Sign uplog insign up
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

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

level 2

If you are pinging by address ("ping 192.168.1.248") 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
[deleted]
1 point · 8 days ago

[removed]

level 2
Moderator of r/networking, speaking officially1 point · 8 days ago

Thanks for your interest in posting to this subreddit. To combat spam new accounts can't immediately submit or post.

Please DO NOT message the mods requesting your post be approved.

You are welcome to resubmit your thread or comment in ~24 hrs or so.

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

Community Details

127k

Subscribers

1.1k

Online

###Enterprise Networking Routers, switches and firewalls. Network blogs, news and network management articles. Cisco, Juniper, Brocade and more all welcome.

Create Post
r/networking Rules
1.
Rule #1: No Home Networking.
2.
Rule #2: No Certification Brain Dumps / Cheating.
3.
Rule #3: No BlogSpam / Traffic re-direction.
4.
Rule #4: No Low Quality Posts.
5.
Rule #5: No Early Career Advice.
6.
Rule #6: Educational Questions must show effort.
Cookies help us deliver our Services. By using our Services or clicking I agree, you agree to our use of cookies. Learn More.