In reply to a post by pyarwood:

having 2 dhcp severs wont cause problems if they are configyred correctly

Most home routers don't let you change the default router (gateway) that the DHCP issues. You can control the size of the scope, but that doesn't help you. For these two reasons, the standard recommendation is "turn off DHCP on your old router being used as a WiFi access point".

If you run DHCP on a full computer, or Raspberry Pi or NAS box, or something else, usually full configuration is possible.

In reply to a post by candlerb:

Whether the router does NAT or not is unrelated to this. The host can *only* ever create ethernet frames addressed to other devices on the same LAN, and it encapsulates datagrams to the "next hop" device on the same LAN.

Where the "netstat -rn" command is quite useful, from the *nix world, it usefully works on Windows since NT (whereas Win95/98 era required the odd "route print").

That's old school. "ip route [-6]" is what modern Linux distros use.

Under Ubuntu, you need to install "net-tools" to get the legacy tools (netstat, route, ifconfig, arp ...etc)

In reply to a post by candlerb:

That's old school. "ip route [-6]" is what modern Linux distros use.

Agreed, "ip addr" is a lot easier to remember, however the "ip" command isn't (yet) cross platform.

Under Ubuntu, you need to install "net-tools" to get the legacy tools (netstat, route, ifconfig, arp ...etc)

I'm mostly on RHEL derivatives, Rocky etc, and It appears it is also "net-tools" that I use with dnf.

In reply to a post by jchamier:

"ip addr" is a lot easier to remember

and "ip a" easier still

In reply to a post by DFScale:

and "ip a" easier still

great for obscure scripting too.

In reply to a post by jchamier:

great for obscure scripting too.

Fair point. I think this marks a point where I would script differently from how I use the CLI

I have, ( and this will blow some minds) three DHCP Servers, one is UltraHub, one is a TPLlink on the same subnet they have the same DGW (default gateway) and no overlapping address space, both have 24 hour lease. It’s curious that the TPLink seems (due to IP Addresses) to supply, most but not all of the IP addresses.
The third one is connected to one of the boosters, this is setup has an IP Router, the LAN side has a DHCP Server obviously setup to a different Subnet. On this LAN there is a lot of local media traffic which kept away from the first subnet (yes I know switches segment traffic) ounce and for all. One of the reasons for the second LAN is the SKY Q-Boxes you can get issues with 4K videos on busy networks. The devices on second LAN can reach the Internet.
All SKY Equipment is setup on copper with Fixed IPs
Yes I know about possible double NAT issues with some gaming apps no one plays games on the second LAN.
If you want to know about DHCP and have a week to kill download RFC2939 it was updated only a couple of days ago, seriously do what I do use it as a reference for the bits you need.

The problem with all of this is those routers are unlikely to properly to conform to standards or expected ways of working so you are adding a lot of unknowns into all of that. Whereas vendors like Cisco or Microsoft (Microsoft DHCP) will do a fair bit of testing those routers will literally only be tested for home user and probably never tested against interacting with any other device types on the same network. You can look at it all theoretically and say it should work but the real world often throws unexpected issues up.

With all network issues you strip equipment out down to the bare minimum one Ultra Hub Router , re-run tests and record results. Introduce items of equipment re-run tests and record results, keep doing this till you reach the desired topology.
During the above, speed tests were carried out and apart from the normal deviation with multiple tests, they were all similar with no major deviation.

Carried on inspection just to be sure.

Run Wireshark for any unpredictable frames, record the traces, move Wireshark around the network and do same.

Check error logs that are available for any lan and WiFi issues, only annoying entries in the WAN logs loads of entries from various IPs trying to open well known and obscure TCP Ports within the Ultra Hub, been thinking about a firewall with a blacklist.

Run JPERF between lan hosts for lan throughput record results, got what was expected.

Run various IP Scanners physically verify all listed MAC Addresses.

Run ping test between various points on the network while running Wireshark filtered to ICMP, this will give you lan traffic timings, again what was expected. Tried different sizes, large ones to force fragmentation no issues.

Large portion of the traffic is over copper.