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Re: Strange issues with DHCP leases and machines registered as on my LAN in Orbi router?

kingtj
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Strange issues with DHCP leases and machines registered as on my LAN in Orbi router?

(I believe my Orbi router is an RBK43 system, although the Netgear message forum isn't letting me select any modfel other than the RBK53.)

 

But anyway, my issue is this:  I've got a fairly good sized network in my house, since we have a family of 6 and a lot of devices (maybe around 70 or so total, when you factor in things like some home automation switches and plugs, Ring doorbell and chime accessory, smart TVs, etc.).  All of this works pretty well with my Comcast gigabit cable modem and Orbi setup, except for one strange issue that seems to rear its head every month or two. I have a dedicated server in my cellar running FreeNAS 11, with several virtual machines hosted on it for a Plex media server, a NextCloud server and a HomeBridge server appliance that allows a few things like my "MyQ" garage door opener to work with Apple Homekit.  The FreeNAS and the virtual machines on it are each assigned reserved IP addresses on my LAN, in the Orbi, based on their unique MAC addresses in DHCP.

 

Well? Occasionally, I run into weird situations where I can no longer access the web interface for my FreeNAS server.  It just times out like it's not online. Yet if I ping it, it's still responding. And typically, the other virtual machines are still accessible too - which also proves the server is still running and communicating.  I discovered if I reboot the Orbi router, all of these problems vanish.

 

So the last time this happened to me, I did some more investigation before just rebooting it.  I realized I could still pull up the FreeNAS web panel if I accessed it by its hostname in my browser, instead of by specifying its IP address.  Nonetheless, it was still using the correct IP address!  And when I got in to the FreeNAS that way, I discovered it was unable to resolve any hostnames either. (Its DNS was set to the IP of my Orbi router, which normally lets it resolve DNS just fine.)

 

When I pulled up the Orbi's web panel and looked at its list of systems it believed were on my LAN?  It looked like it had some incorrect information.  My FreeNAS server has a hostname on my lan of "freenas" - but the Orbi was showing that hostname linked with a different IP address than the one reserved for it.  It also showed a hostname of a computer I'd sold to someone weeks ago, paired with an IP address that was in use by a different machine on my network.

 

As I found before, rebooting the Orbi router got things working properly again, and another look at the list of systems on the LAN semed to be current and correct again.

 

So .... what's the deal here?  Is this some kind of DHCP bug in the Orbi firmware that it stops updating its list of hosts on the LAN and their associated IPs after a while?  Do I just have too complex a network for it to handle reliably over time?

 

Model: RBK53|Orbi AC3000 Tri-band WiFi System
Message 1 of 5
FURRYe38
Guru

Re: Strange issues with DHCP leases and machines registered as on my LAN in Orbi router?

What happens if you set a new default IP addrss pool of 192.168.1.100 to .200, then set a static IP address ON the NAS device of 192.168.1.2?

Static IP addressed devices need to be out side of the default IP address pool while IP reservations are with in the pool. 

My Setup ISP SparkLight | Internet Cable 1000↓/50↑ CAX80 Modem Mode |  Wifi Router RBK953 (Router Mode) 2.5Gb Wired Backhaul | Switches NG GS105/8, GS308v3, GS110MX and XS505M | 

Additional NG HW: C7800/CAX80/CM1100/CM1200/CM2000, Orbi: CBK40, CBK752, RBK50, RBK853, RBK752, RBK953, SXK30 | NightHawk: MK63, R7000, R7800, R7960P, R8000, R8500, RAXE500, RAX50, XR450, EX7500/EX7700

Message 2 of 5
tomschmidt
Virtuoso

Re: Strange issues with DHCP leases and machines registered as on my LAN in Orbi router?

I likewise have found that the Orbi's DNS server is not configured properly for resolving local hostnames on the LAN.  There is a workaround (see https://community.netgear.com/t5/Idea-Exchange-For-Home/orbi-add-dns-server/idc-p/1632085#M1731 for details).  The DNS server of the Orbi cannot translate hostnames to IP addresses.  For example, try the commandline "nslookup freenas" on the Windows CMD line or on a Linux command line.  You will see that the name resolver of the Orbi cannot resolve local LAN hostnames.  I have an open ticket with Netgear for this major issue for over 11 months, and they have so far refused to fix it.  DNS resolution of local hostnames on a LAN is a basic router function that is broken on the Orbi.

 

Regarding an old host still appearing in the list, do you have an Address Reservation defined for it?  If so, delete the old Address Reservation for the device that you no longer own.

RBK53 Orbi AC3000 Tri-band WiFi System (RBR50v1 router and two RBS50v1 satellites) running v2.5.1.16 firmware
Model: RBK53|Orbi AC3000 Tri-band WiFi System
Message 3 of 5
CrimpOn
Guru

Re: Strange issues with DHCP leases and machines registered as on my LAN in Orbi router?


@kingtj wrote:

(I believe my Orbi router is an RBK43 system, although the Netgear message forum isn't letting me select any modfel other than the RBK53.)


You are correct. The Netgear forum "product pull down" is woefully inadequate, a frequent source of frustration.  Just a tiny clarification, RBK43 is the product name for a package containing one RBR40 router and two RBS20 satellites.

https://www.netgear.com/images/datasheet/orbi/RBK43.pdf 

 

There have been several posts regarding Orbi DHCP behavior.  For certain, Orbi checks that an IP address is in use when processing a DHCP address before checking the LAN IP Reservation table.  This annoys me often when I have assigned an IP to a device and suddenly find that it has a different IP or that a different device now has the IP I assigned to that device.

 

One thing to check: Are the assigned IP's in a different number range from the general DHCP pool?  It seems to be a reasonable practice to set aside a range of IP's for these devices, and set up the DHCP pool in a different range.

 

No. 70 devices are not too many.  People have reported over 100, and the Orbi documentation mentions being able to handle a full DHCP subnet of 250 IP's (actually 249 because 250 is "special").

I love my Orbi.
Message 4 of 5
kingtj
Star

Re: Strange issues with DHCP leases and machines registered as on my LAN in Orbi router?

Thanks for all of the information!  I hadn't realized before that the Orbi was unable to resolve local hostnames via DNS.  That's definitely a really disappointing omission!  That work-around is interesting but not sure I want to rely on that since it doesn't survive a router reboot.

 

It does sound like the best solution for me is to just go with static IP assignments for my server and its VM's, and to stop relying on the Orbi to "pin" those IP addresses via DHCP reservations.  At one time, that's how I had things working and that worked just fine.  (As others said, you just make sure the DHCP scope doesn't include the area where you put your static assignments.)


I believe the reason I went away from that was some difficulty with the FreeNAS virtual machines accepting static IPs, though?  There's some additional complexity getting them to properly take the rest of their settings (default gateway, etc.) when they're configured with a manual IP assignment instead of just grabbing everything they need via DHCP.  You wouldn't think that would be a big deal ... but between doing a network emulation and trying to support IPv6 as well as IPv4 and idiosyncracies of the FreeBSD operating system, I had some hassles.

 

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