On my new HE, there is no option for setting a static IP address. Other postings have suggested setting up my router to always assign the same IP to the HE, based upon MAC address. I can certainly do this, but I was concerned about the scenario where the hub tries to obtain its permanently assigned IP from the router via DHCP, but the DHCP service is not yet running on the router.
I used to run into this issue with my Wink version 1 hub on occasion. If WIFI was not up when the hub booted, it would hang and become unresponsive, requiring a manual power reset.
Some devices will default to a predetermined local IP address on the private IP address ranges. Many will give up on using DHCP once that happens.
Will the HE eventually assign its IP address via DHCP, even if the router running the DHCP server is not yet available when the HE boots?
A device will try to use its previously assigned address if no DHCP server is present and the reservation time isn't expired. I don't know of a specific issue with HE. Do make a reservation as there are no facilities for adding a fixed address in settings.
Thankfully HE is not wifi, plug the hub into the router/wired switch for best results (excludes wifi relay/AP mesh). But what @zarthan said still applies.
Hubitat doesn't have a way to assign a static IP address on the hub side (this is probably for the best since there is also no hardware-only way to reset it, like a "reset" button, if this needs to get cleared or something gets messed up). A DHCP reservation on your router side is really the only option if you want one for this reason. Hubitat is wired, not Wi-Fi, so if your router/AP is like mine where the wired portion comes back up sooner, you might not run into this problem like you did on Wink. (Someone beat me to this above as I was trying the below. )
I can't speak to the behavior of the hub if this does happen but can say that it never has happened to me. For fun, I just tried plugging my spare hub into a switch with no router connection and seeing what happened. I don't have anyway of knowing what it did during that time, but when I plugged it back into my "regular" network, I was able to access it at the expected IP address within seconds (it's reserved on my router, but the lease time would have been up--it had been offline for days--and on the Hubitat side I assume that's all it would have known). So, without staff confirming any software oddities here, I'd say @zarthan's comments would apply.
It appears that the hub remembers its last-assigned IP address and uses it if it cannot contact a DHCP server, regardless of timeout status of the lease. If so, reserving the IP at the router to be sure the IP is not assigned to another device is sufficient.
In fact my router DHCP and wired LAN ports become active much sooner than the WIFI. I used the Wink as an example, since the DHCP server was being blocked by lack of WiFi access.
I have my house wired for Ethernet and POTS telephony through a patch panel and managed Cisco switch in the basement, so there is the boot time of the Cisco to consider as well.
It sounds like all the bases are covered with the HE, though.
Does that mean you can disconnect the hub from the router, hook directly into a computer and access the hub?
Reason I’m asking, working with a friend about setting up a unit in a green house to control some ventilation and lighting. He won’t have a router there. Wondering if I can then take my laptop and hook directly to the hub if changes are needed. Realizing of course I have to manually assign my laptop ip and probably a cross over cable.
Good question! I wonder if the unit would remember the previous network configuration after a reboot, with no DHCP server attached. I have a few crossover cables. I’ll give it a shot with my laptop.
I had to take a drive with my hub a little while back... Long story... and found that it would lose its IP address if it was disconnected from the network. So I know that you cannot connect a hub and a computer together via a switch without the DHCP on the same network. I suspect that connecting the hub directly to the computer would not work either, but haven’t tried that (would require an inverted cable which I didn’t have at the time...)
Just an FYI...crossover cables haven’t been needed to directly connect Ethernet ports between two devices for a very long time. All modern Ethernet ports are auto sensing, auto crossover. So, chances are very good that a normal Ethernet patch cable would just work. As long as the computer that the Hubitat hub is connected to is running a DHCP server and a NTP server, it should work...
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