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: https://www.reddit.com/r/techsupport/comments/96kx3s/dns_andor_dhcp_issue/