Changing WIFI, concerned about impacts to installation & IP changes

RPi 4, recently migrated older install to new RPi4. All is fine with the new device (thanks for all the help getting this far!) I had gotten myself into trouble with my old install by not getting instructions here first…so I here I am!!!

My WIFI router is aging (and rented from my provider). I have purchased my own and the cable provider tech will be coming by later to install. Long story, but since my phone is through them, the tech needs to do it and the existing router will remain (for phone only). I do not know if I can run the two wifi networks or not concurrently.

Here is my question: I have the RPi’s IP reserved in my current DHCP configuration. I suspect that will be replaced and I am unsure of whether or not I can assign that same IP with the new router. I use putty to get to my RPi, which won’t work without WIFI. I am concerned that at the point of cutover, I will be unable to get to the RPi. SO…do I need to plan on using ethernet to get to it? Should I then use openhabian-config to adjust the WIFI connection? If I plug in ethernet, can I do that hot or do I need to reboot?

What if I need to adjust the IP address? How should I do this?

I could set up a WIFI hotspot on my main computer, switch RPi’s WIFI connection to use that one during the cutover. Is that a reasonable approach?

Guidance, please. I REALLY like (and depend on) my OpenHAB installation and I want to make sure I protect it.

Wow. You’re me. Nice to meet you!
Long story short, you pick a paper and Pen, open your router config page, and take note of all devices + their ip.
(You can also run the cmd arp-scan =localnet and wait while it maps the network but you will probably get more data on the router).

This way you have each device + each IP.
When your router is replaced you change the Wi-Fi SSID to the name of the previous one, and change the password to the old password, and all devices will now connect to the new routers Wi-Fi.
Then you go to (probably) to the new router DHCP options, look for each device, and set static IPs for each device, and assign the old ip for each.

Then you think how this was all a waste, google how to have an internal DHCP server in your network, install pihole, turn on dhcp, and you never have to worry about this, again.


Normally you access your PRI by hostname, not by IP address. So in theory the IP address does not matter.
However, you seem to be concerned and that needs to answered. Therefore I suggest to inform the cable provider tech about your concerns and ask him to ensure your RPI will be assigned the same IP address as before even after the WIFI router is exchanged. He should be capable of solving that request.

Thanks for the advise! I have captured my current configuration. I think my RPi , my security camera and my bobcat miner are the only ones with any IP connections…so hopefully all will be good. Question on pihole – is it safe to install with openhabian? I had taken so many wrong turns early on with my initial install that I’m a bit gun shy about installing anything unless I confirm first that it is an “ok” install.

I am hopefully that I can use re-use the old SSID/passwords. That seems like the smoothest path. Network changes are fraught with terror…

While I myself tend to host a lot of services from the same host machine (mainly to keep energy consumption low) I would highly recommend to at least use a dedicated Pi zero or similar for the task. You don’t want to have your DNS and/or DHCP server going down when rebooting/shutting down your OH machine for whatever reasons. I run two Pi zero (without the W) as redundant DNS servers (synched via gravity-sync: GitHub - vmstan/gravity-sync: 💫 The easy way to synchronize the DNS configuration of two Pi-hole 5.x instances.) It’s really cheap hardware and saves you a lot of trouble (and blocks advertisements if you like).

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I’m guessing that the technician is going to disable the WiFi on the modem/router, plug your new WiFi router in via an Ethernet cable, and set it to Access Point (AP) mode. If they do this, then your old modem/router will still be your DHCP server and your reservations will still be in place. This is how my network is set up, as my modem/router also provides my cable TV service.

Alternatively, they might put the old router into Bridge mode, in which case your new router will be the DHCP server and you’ll have to set up the reservations on it. I’m doubtful of this, because ISPs usually (and understandably) want to keep things simple for troubleshooting purposes.

I’m running PiHole with openHABian, but I don’t use it as a DHCP server. If I were, I’d run it on a separate machine as @DrRSatzteil recommended. There’s nothing wrong with PiHole’s DHCP, but there’s also no significant advantage to it over your router and it’s another potential point of failure. If my openHAB/PiHole server goes down, I just have to reset my DNS to the default and live without adblocking for awhile.

Honestly, I wouldn’t jump into PiHole. If your old modem/router is still your DHCP server, nothing changes for the rest of your network. If your new WiFi router is the DHCP server and it’s easy to set up reservations, then you can quickly be back to normal without too much fuss. Get it all stable, then look at adding PiHole later if you want the adblocking features.

As always, words cannot adequately express my appreciation for the assistance. This community is amazing. And appreciated!

Task is done, no problem. We disabled the old router’s WIFI, brought up the new one using the old SSID and password. The RPi came in with the correct IP, and we immediately added a reservation to hold it. Everything worked flawlessly. I am much happier with my new set up…especially because OpenHAB is operational. My new router is handling DHCP and, at this point, I don’t feel compelled to add anything more to the mix. (If it ain’t broke…don’t change it) I will keep Pihole in mind, but don’t feel a need right now.

Again, thank you all.


Awesome!! :smiley: