Mobile Hotspot Repeater?

I have a complicated setup I need help with. I have tried this before and failed. Now I need it set up. Here is a picture of the setup I'm needing (I have all the hardware)

I remember trying something with a repeater function but I didn't route it to a new wifi connection, I believe I only bridged it to ethernet.

Mobile Hotspot (internet)

WIFI1 (192.168.X.0/24)
ssid - network1

OpenWRT (router)

WIFI2
connected to network1
IP : 192.168.X.150

WIFI3 (192.168.0.0/24)
ssid - network2

Device1

connected to network2
ip : 192.168.0.2
internet routed from WIFI2 which is connected to network1

Device2

connected to network2
ip : 192.168.0.3
internet routed from WIFI2 which is connected to network1

Device3

connected to eth1
ip : 192.168.0.4
internet routed from WIFI2 which is connected to network1

The reason I am needing this is because I have a home surveillance system that needs a constant wifi connection. My mobile hotspot is my only source of wifi and there are no ISPs where I live so using a dedicated wifi router would be useless. I need my internet provided to my devices when I am home, but when I am not home I need them to still be connected to the same wifi network. Any help would be greatly appreciated.

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I need the same setup for my home with my Android hotspot. I tried this tutorial https://openwrt.org/docs/guide-user/network/wifi/relay_configuration. However, I stuck until the subsection Configure static IP address on wwan interface.
Have you already solved it?

Can't usually be done, since the phone doesn't expose the setting.

Thanks @frollic for the fast response!
Can a setup with two OpenWrt routers solve this issue? Like this tutorial https://openwrt.org/docs/guide-user/network/wifi/atheroswds that one router as AP is connected to a mobile hotspot (DHCP) and a repeater that provides the static IPs.

What are you trying to achieve, with what device + cell phone ?

Why not simply connect your openwrt device to the phone wirelessly.

My goal is to connect my Samba NFS with my home devices, such as printers and laptops. Since I don't pay any cable Internet provider and only use my flatrate mobile internet at home, I have to connect my samba server on my laptop to my Android mobile hotspot to my printer. I assign the IP of my laptop to the printer and everything worked well until I restart my Android phone and the the printer doesn't recognise the IP anymore. In order to solve the issue I have to assign my laptop name instead of the IP number, smb://pcname/shares instead of smb://192.168.X.X//shares.

For that reason, I read about OpenWrt and flashed the OpenWRT for my TP-WR902AC. I thought with OpenWRT I can solve the issue, until I stuck on that section with the static IP on the WWAN interface.

Thus, the main goal is to have a static IP for my devices on my local network that connected to the Android DSCP hotspot. I can buy a new router for the second OpenWrt router if that can solve my problem.

Not sure if it'll fit the flash of your 902, but try this instead https://openwrt.org/docs/guide-user/network/wan/smartphone.usb.tethering

Or just do a scan -> join in the wifi section on the 902, join the phones wifi, and put the new connection in the wan zone. This could however break the wifi of the 902, not all radios are capable of running as client and AP at the same time, trial and error.

But yes, it's definitely solvable with openwrt.

The USB tethering doesn't suitable for me since I need my phone to be carried on everywhere.

Yesterday, I can setup my OpenWrt-902 to be a wifi extender from one Radio using different SSID. However, all of the devices have the same IP prefixes 192.168.X.X as from my Android hotspot (no subnet).
How should I setup the wireless configuration for one as client mode (joining phone wifi -> Interface network config: wwan) and one as Access Point mode? In the Network Interfaces I have LAN and WWAN interfaces. Should I create a new interface called WAN? If yes, how can I connect the WAN with WWAN of my Hotspot client? Should I utilize the relayd package by bridging?

That would probably be because the connection to the phone wasn't put in the wan zone.

if you can scan and join, you already have the wifi there, just need to set up the security, rename and enable it.
but like I said, there's no guarantee it will work in both modes at the same time.

With these settings I can have a wifi extender with OpenWrt as a new SSID.:

  • The OpenWrt SSID has Access Point/Master mode and is assigned to the lan network interface:
  • The Hotspot DHCP client (Network Y) has the client mode and assigned it wwan network interface.
  • The lan network interface uses static address and is bridged to the wwan network interface:

After I changed the network of Network Y in the interface configuration from wwan to wan, I see this error and can't connect to my 902 through 192.168.1.1 anymore.

Is that what you meant that running as client and AP at the same time can not be possible?

Ah, the device have two radios, then it's doable.

depending on your phone, you might want to swap the radio acting ap/client.

Create (or edit the existing openwrt one) a new AP, on the nac radio, set the SSID,
key and password.

connect to the nac radio (or via the ethernet port), and do the scan -> join on the
gbn radio, put the connection in the wan zone.

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The "wan zone" you wrote, does it refers to the firewall zone or the network interface?
My hotspot can be detected by the bgn radio. If I click join, the first modal interface shows the firewall zone:

Is that what you meant that it refers to the firewall zone? or does it refer to the network configuration interface "wan" under the tab "General Setup"?

yes, it does.

Under the Interface Configuration -> General setup, should I assign "wwan" as the network or "wan"? The default is "wwan". I set it to wan zone and wan network. Afterwards, I don't see any entry under the Associated Stations.
The firewall of the wan zone has reject for Input and Forward. Shall I set it to accept?

wwan as network, wan as firewall zone.

The client on the gbn radio is successfully connected to the hotspot wifi on the wwan network interface.
I'm still struggling setting the new AP on the nac radio. I tried several time with different network interfaces, and the AP can't provide an IP address for my device.
Should I assign this AP wifi on the nac radio to the wwan or wan network interface?

the default settings where/are all fine, only adjust the name of the wifi, encryption, and password, of the disabled, but already existing, openwrt SSID.

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Thanks @frollic !!
After several failed trials on the AP wife on the nac radio, I reflashed my TP-WR902AC and just performed these steps to create a subnet which has different IP prefixes from the hotspot dynamic IP:

  1. Network -> Wireless -> bgn radio -> scan -> join the mobile hotspot -> insert the WPA password of the hotspot and let the default settings (firewall wan zone and wwan network interface).
  2. Edit the existing wireless network "OpenWrt" on the nac radio -> change the SSID name if it is desired, activate the encryption to WPA2 or WPA3 and add a new password. Let the default settings (lan network interface).

That's all! No need of relay bridge or editing the LAN interface at all!

My failure was that the default wireless on nac radio was deleted. If we add a new wireless, the network is assigned as unspecific network. Then I tried to assign it to wan or wwan, which doesn't work. I did also several experiment in the interfaces by using the relay bridge, usw.

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