Orbi WiFi 7 RBE973
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gadgets on orbi RBR750's wifi can see DHCP; server on local ethernet only works with IP addresses

jc1742
Aspirant

gadgets on orbi RBR750's wifi can see DHCP; server on local ethernet only works with IP addresses

A bizarre problem has popped up in our local (house) network:  Our Orbi RBR750 is attached to a local ethernet (CAT5/6 + 2 switches).  The web server on the cable can see outside, so its web browsers and commands (ping, traceroute, ssh, ...) work only with IP addresses, not hostnames.  Yesterday morning names worked there, then suddenly they didn't.  I can do things from it like ssh to machines on wifi or fiber (using the IPaddrs, and once a window is logged in on one of the wifi gadgets (e.g., a several Macbooks, I can then ssh out to remote machines where I have an account, using their hostnames, and it works just fine.  But the same ssh command typed to the local wired server machine fails with any of several messages.  A test just now got "No route to host", others have got "Network is unreachable".  But indirecting through a wifi login to a local machine, then sshing from there to the remote target succeeds.

 

I've been poking around in various documents (like the RBR750's online manual), asking google about it, etc. have turned up no clues so far.

 

Is anyone familiar with this sort of failure?  I'm assuming I did something wrong in my ongoing efforts to make the web server visible to the public, but I haven't found any clues so far.  So I thought I'd ask the experts here.

Message 1 of 6
jc1742
Aspirant

Re: gadgets on orbi RBR750's wifi can see DHCP; server on local ethernet only works with IP addresse

I forgot to mention that the server machine is an Ubuntu linux box.  Most of the other machines are various Apple varieties, plus one Windows machine, and assorted ios  and android gadgets.  (And a flock of Alexa thingies, but they're another story. 😉

Message 2 of 6
CrimpOn
Guru

Re: gadgets on orbi RBR750's wifi can see DHCP; server on local ethernet only works with IP addresse

Some of the description is ambiguous (to me  I'm a visual person.)

 

It would be helpful to have a diagram of this network, showing the Internet Service Provider (ISP) device, the RBR750, the switches, the Ubuntu server, and other devices.

 

It is customary to ask what the ISP device is and what 'mode' everything is in. (router, access point, pass-through, etc.)

 

I love my Orbi.
Message 3 of 6
Mikey94025
Hero

Re: gadgets on orbi RBR750's wifi can see DHCP; server on local ethernet only works with IP addresse


@jc1742 wrote:

A bizarre problem has popped up in our local (house) network:  Our Orbi RBR750 is attached to a local ethernet (CAT5/6 + 2 switches).  The web server on the cable can see outside, so its web browsers and commands (ping, traceroute, ssh, ...) work only with IP addresses, not hostnames. 


Yes, a network picture will help us understand.

  1. Is your Orbi running in Router or Access Point (AP) mode?  If AP then DNS is handled by your router and not your Orbi.
  2. It sounds like you have some devices outside (upstream) of your Orbi network.  Are these devices, like your web server, connected to your [Cat5/6 + 2 switches] network rather than behind the Orbi network?
  3. If yes then what is handling their DNS and have you considered putting everything inside your Orbi network?
Message 4 of 6
jc1742
Aspirant

Re: gadgets on orbi RBR750's wifi can see DHCP; server on local ethernet only works with IP addresse

Hmm .. I thought I replied to this, but I don't see the reply.  Well, I'll summarize:

 

Our Orbi (RBR750) is plugged into the ISP's modem, and the folks there (RCN) say it's a simple modem, not a router. The Orbi has the usual 192.168.*.* wifi flock, plus there's an ethernet cable running from the Orbi to a Netgear switch (FS605 v3) that has a couple of other gadgets attached, including a linux web server.  The other machines involved are e Macbooks, all on the Orbi wifi, and all of them (suppoosedly;-) use the Orbi as their DHCP server. In other words, they're all inside the Orbi's network. Sometimes they can reach each other by name; at other time only by IP address, and the pattern seems rather random, not associated with anything I'm doing on them. 

 

Oh, and  they all have fixed IP addresses (though a couple of them  also have dynamic addresses on the same port, if that signifies anything. I'm not sure what causes this on some but not all of them.)

Message 5 of 6
CrimpOn
Guru

Re: gadgets on orbi RBR750's wifi can see DHCP; server on local ethernet only works with IP addresse


@jc1742 wrote:

. Sometimes they can reach each other by name; at other time only by IP address, and the pattern seems rather random, not associated with anything I'm doing on them.


Actually, this may be exactly the issue.  There are several ways devices"find things" on a network:

  • The most obvious is using a Domain Name Server.  i.e. "where is ford.com?"
    The Orbi DNS will resolve only internet names, not "local" names.  This comes up more frequently than one might imagine. Someone wants to open a web browser to "local:mywebserver".  There ARE DNS servers that can do this, such as Pi-Hole. (and maybe pfSense? I have never looked at it)  But, the Orbi DNS resolver cannot.
  • Windows machines often find other Windows machines using a naming system unique to Windows.
  • Media servers often use some sort of IP multicast to let users know where to find them.

In other words, I doubt that this is truly 'random'. i.e. does the same method find another machine "by name" some times, but not other times?

I love my Orbi.
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