Static IP with a DHCP port

**aljames2** · February 10th, 2024

Have you considered hanging a multiport dumb (unmanaged) switch off the port you want to use, you could have your desktop and server on the same subnet that way, if that is what you prefer.

As mentioned, you can set a static IP on the server using your nteplan .yaml file. Some examples here: https://netplan.readthedocs.io/en/stable/examples/

There are errors in your attempt as shown. You cannot assign the same IP address to your server interface as the router interface on the subnet. As TheFu said, 78.84.xxx.xx is wrong, not in the range of private IPv4 addresses, something wierd there.

Is your ISP provided router also your modem? If so, and you wish to use your own router, you will likely need to put the ISP router/modem in bridge mode and then put your new router behind that. If you have a separate modem already, then yeah, you can probably ditch the ISP router and use a new one.

**TheFu** · February 10th, 2024

Originally Posted by dabelort

I consulted with my ISP (they have made the routers basically unchangeable by the user and wont give me access to change anything myself) and seems like my best course of action is to get a new router with which to try again, so for now i wait till i get the new router and will try again, but thank you for the advice and help!

I new router isn't needed and won't provide the necessary knowledge. Just setup the correct static IP on the system.

If your understanding of IPv4 networking is weak, episode 25-29 (approx) of the Security Now! podcast will explain it.

**CharlesA** · February 10th, 2024

Censored the public IPs after the OP asked.

Having a /19 is a bit odd for sure. I've got a /30 at home and a /29 at work.

What ISP do you have? Do you know the model of router did they provide? If you are trying to set up another device to act as a router, the other router should be set into passthrough mode if possible.

**MAFoElffen** · February 11th, 2024

What is even more odd, is that you are trying to set the IP via DHCP. Did you not pick up on that? That is not what people usually do or are set on as a requirement.

The more normal/accepted method is to set the IP as Static, from the machine itself.

**TheFu** · February 11th, 2024

Originally Posted by MAFoElffen

What is even more odd, is that you are trying to set the IP via DHCP. Did you not pick up on that? That is not what people usually do or are set on as a requirement.

The more normal/accepted method is to set the IP as Static, from the machine itself.

Well, it is 50/50 - static assignment on the system or DHCP reservations. I've seen both used in corporate environments. I've also seen a corporate campus crashed because their redundant DHCP servers failed. 2000 systems and none worked.

Definitely best to set static IPs on each system, provided that system doesn't move. For laptop, using DHCP reservations is probably smarter.
Back in 2011, I thought using DHCP reservations was a great idea for home. https://blog.jdpfu.com/2011/07/18/us...ice-management even after seeing that massive failure around 2005 at a client.

Then I messed up my DHCP settings at home and none of my system would get an IP. That's when I decided to add my caveat.

Servers/Desktops - static IP configured on the device.
Portable devices - DHCP Reserved IPs, configured in redundant DHCP servers.
Devices that don't allow setting static IPs - DHCP Reserved IPs, configured in redundant DHCP servers. Mainly IoT stuff.