Redundant Cellular setup

[sanj3k]

Hi everyone, I have stumbled upon your project and set yesterday the vps plus router up. Today i went through the issues and discussions with some keywords because there weren't 1:1 guides for what i think i want to achieve.

Let's start first at least as of right now i have only a raspberry pi 3b. As far as I know it's not ideal for superb bandwidth but i don't intend some speed records I only need the redundancy and failover characteristics like at events where a lot of people occupy the nearby mobile data tower. Is it still extremely bad and I'd really have to upgrade to pi4?

Setup would be raspberry pi as the router who opens an access point to which i then connect my device to have a stable connection. For the links i wanted to go with low-mid priced 5g android phones which have different carrier sim cards. Now comes already the first issue i have found long time ago and wanted to ask if it still persists. Android USB Tether used a hardcoded gateway IP which causes problems since we need different subnets. If this is still the case the only option would be to have adapters to rj45 and then run Ethernet cable with a rj45 to USB a into the pi or say to a switch, right? Only other option would be to open a wifi hotspot from the other phones. I like the idea with the phones as they are more compact than the modems partially even cheaper etc

Besides that are there other things to look out for? Setting up the GUI to the redundant mode and one connection will be the preferred (master) one. There was one issue where one guy tried to simulate the connection loss and he had problems after the failover. Has this been resolved and or can you instruct me what i have to do to see if everything works as intended?

And last topic somewhat similar i know there are these speed tests like aggregates or per wan but if I'd want to make a somewhat real life test in my subway drive to work. I know several spots where the signal is somewhat there but internet not at all (even above ground) and after a certain station there are also a lot of people who may occupy the cell tower too hard. So this would be an ideal scenario to run some kind of logging and or monitoring the connection of my single device which becomes somewhat totally unusable and if with the bonded connections it would work. How would you structure this kind of a test.

Thanks a lot already to everyone and I also hope that this discussions thread can be used for other people finding out about this project who may have the same questions as me.

[sanj3k]

Also I may need help setting up the openwrt AP in the wiki a device is activated and in the network interfaces tab then it has already an ipv4 address assigned thats not the case on my machine. Or can I choose on as long as it's in the same subnet as LAN so I can access the web interface over WiFi.

In my iphone the circle just rotates but never connects really to the openwrt AP. In the web interface I can see a device showing up and also in the systemlogs it says something about an Established handshake but unfortunately as said the iPhone doesn't want to connect