New router after a plan change: what you lose
A replacement router from your ISP arrives blank. Before the old one goes back, screenshot four screens — or your CCTV cameras, printer and remote access go dark.
You change plan, the technician arrives, the new router goes in, and the internet works. Speed test looks healthy. Everyone is happy for about six hours.
Then at nine at night someone says the CCTV app shows the front gate camera as offline. The printer has vanished from every laptop. The smart plugs are blinking their pairing lights in the kitchen. The WiFi name on your phone is now something like TP-Link_4F2A with a password nobody has written down, and you are standing in the hallway holding a router manual you did not ask for.
None of that is a fault. A replacement router arrives as a blank box, because every setting you ever made lived in the old router's memory — not on your line, not in the cloud, not with your ISP.
The ten-minute inventory, before anything is unplugged
This is the one step worth doing today, while the old router is still powered on and still answering. Do it on a phone or laptop connected to the old network.
- Open the device list. Log in to the router's admin page (usually
192.168.1.1, or the ISP's app) and find the list of connected devices. Screenshot it. You want the names, the MAC addresses, and which band each one sits on. - Screenshot the WiFi page. Network name, password, security mode (WPA2 or WPA3), and whether 2.4GHz and 5GHz currently share one name.
- Photograph the fixed addresses and forwarding rules. DHCP reservations and port-forward rows are the two things nobody remembers and everybody needs. A photo beats your memory of a port number.
- Write down the old router's LAN address. Something like
192.168.1.1. You will want to know at a glance whether the new one uses the same or a different one.
If the swap has already happened, you can rebuild most of this by walking around the house with each app open — it just costs an evening instead of ten minutes.
What actually breaks, in the order it complains
| What you lose | Why it bites | Where it lived |
|---|---|---|
| WiFi name and password | Every phone, TV, plug and printer has to join again — by hand | Broadcast by the old router |
| Camera and NVR addresses | Camera sits on a fixed address that no longer exists on your network | Reservation on the old router |
| Remote access | "Cannot view away from home" — the app times out | Port-forward rules |
| Parental controls, guest WiFi, DNS | Nothing breaks loudly, so nobody notices until a school night | Router admin pages |
The last row is the sneaky one. Schedules, content filters and a guest network that a visitor relies on all disappear silently. The internet still works, so it does not feel broken — it just quietly stops being the network you set up.
The cause the plan change does not mention: the subnet and the security mode
Two settings that are almost never identical between an old ISP router and its replacement.
The LAN subnet changes. Old router hands out 192.168.1.x, new one decides it prefers 192.168.0.x. A camera, a printer or an NVR configured with a fixed address in the old range is now a stranger on the network. It powers up, it looks connected, and it is unreachable. That is why the camera says offline while your phone happily streams video on the new WiFi.
The security mode moved up. New routers increasingly default to WPA3, or a mixed WPA2/WPA3 mode. Plenty of 2.4GHz-only gear — cameras, doorbell units, plugs, older printers — cannot do WPA3 and simply fails to join, often with no useful error message. Fix it the boring way: keep WPA3 for phones, laptops and the TV, and give the older devices a separate 2.4GHz network running WPA2. Same trick applies to band steering, where one name covers both bands: friendly to a phone, unhelpful to a camera that can only hear 2.4GHz.
Rebuilding it without an evening of misery
Work in this order and most of the work does itself.
- Reuse the old WiFi name, password and security mode exactly. Devices remember a name and a password, not a router. Match all three and the majority of the house rejoins on its own while you make tea. This is also the reason to resist "let me pick a nicer name this time" — that rename is what turns a swap into an afternoon.
- Then fix the fixed addresses. Recreate the DHCP reservations for cameras and the NVR, or switch those devices back to automatic addressing and let them find the new router.
- Then port forwarding, from the photo you took, not from memory.
- Then the quiet stuff. Parental controls, the guest network, DNS. Twenty minutes of work that saves you a complaint later.
One honest option: if the old router is staying with you rather than going back to the ISP, it can often live on as an extra access point — a second WiFi point at the far end of the house for the price of a cable. Ask before the swap rather than after, because once the unit is collected the option is gone.
The golden rule
A router swap is not a hardware event, it is a settings migration. Screenshot the old box first, copy its WiFi name and password across unchanged, and the quiet breakages never happen. Skip that, and you will spend the evening in the hallway with a blinking plug.