This is a story about how I learned that free doesn't really mean free, and routers that aren't yours are exactly that. Not yours.
I'm not looking to drag my ISP through the dirt, as they're universally acclaimed to be bad service providers. I'm sharing my experience here to hear what others think, and to add to the dime of a dozen of other precautionary tales on the internet that maybe, just maybe, you don't need an app for that.
My ISP has an exclusivity contract with the company I rent a property from. The property comes with a preinstalled router. Upon moving into the property and attempting to transfer service, I was told that the preinstalled router was no longer supported. To resolve this, they provided the same model router that other customers rent in lieu of providing their own, free of charge. I was unbothered by this proposition, because my personal router was not compatible either. The replacement worked, had capabilities for local administration, and all the other typical features a router should have. Several months later, the ISP pushed a firmware update to the device that visually put a coat of paint on the admin portal. After some digging, I realized the remote administration page had been removed. I didn't see this as a problem at the time, as it was a feature I always had off, but found the ability to administrate the router remotely on their website. At first, it was simply the ability to reboot the device, but with time, more and more functionality was added to their website. This pattern continued for several more months until a tipping point was reached. Another firmware update was pushed that lobotomized the router's admin portal to nothing more than a way to look at data. The only functionality that remained was the ability to reboot the device. Changing WiFi passwords, port forwarding, disallowing clients, etc. It was all only available via their website. I was perturbed by this change, but it was their router, not mine. Thankfully, I still had all the capabilities the router originally provided (foreshadowing).
In this day and age, every company and their grandparents have an app. I'm no stranger to this concept, myself, having done lots of software development for mobile, web, and general computing environments. It came to no surprise when my ISP released an app that boasted the ability to do all the same operations the web interface provided. What would, however, was when the web portal was shut down, only displaying a splash page for the iOS and android apps. The app is now the only way to administrate the router.
That's when it struck me. My ISP expects their customers to have an internet connection to administrate the router. Customers setting up a new router or experiencing an outage are expected to have cellular data to do something as simple as change the WiFi password. I understand how ubiquitous cellphones and data plans are these days, but I personally see it as a failure for an ISP to require something like that.
I was now forced to migrate over to the app. I have an iPhone 6s with the most recent version of iOS. Perhaps some of you can correct me in the comments, but I do not consider that prehistoric. I sucked it up, downloaded the app, but the situation went from bad to abysmal. The app uses an integrated in app browser to authenticate, but the login portal it navigates to requires cookies to function. In short, I'm unable to use the app, so to me, the router was effectively turned into a modem. I purchased a new router, got it setup, and thus ends my tale.
They've also strung me along for probably over a year from one support ticket to another for intermittent failures. As they don't own the copper/fiber network, they would just create a new lowest rung ticket, schedule some contracted third party tech to come out, who would then re-terminate all our coaxial cables, check the connection and leave. This happened about 8 times. I eventually made a real big fuss and they elevated me to some other team, who then booked yet another visit and then didn't show up. I spent an hour to chase this up the next week to learn that they had checked some neighborhood infrastructure and realized there was a failure there and fixed it and gone home with no notice. And just like that the problems were over. Fun people.
Anyway, that's the joy of a hybrid copper/fiber-optic network.