If you act pre-emptively (before you need it for a power failure), you can replace that garbage converter with a non-networked one. I spend two months off-grid in 2022 with solar power running a fridge, lights, computers, and even charging my e-bike. Both of our controllers were non-networked devices.
Also note that a solar panel array with an open circuit voltage higher than the battery they are charging can charge the battery with only a high-current diode (e.g a car alternator diode) as a controller to prevent reverse current flow when clouds block the sun etc. You will have to monitor the voltage manually of course, and increase load or shut down the charge if the battery voltage gets to full charge.
Good chance those networked boxes have some usable parts inside if you know how to build electronic devices. A battery charger for solar panel input is a lot simpler than the pirate radio transmitters I used to build.
Such a system can be used fully off-grid, using either only the solar or only the grid at a time so they are never connected together in the absence of any ability to sync the A/C phase. This is how an RV is done(with or without solar charging the RV batteries): you are on external or internal power but never both at once.
It's also possible to split out some parts of your electrical to run off the solar to its limits, and use the grid for the rest or for loads that are simply too big such as electric stoves or a big central A/C system. Get the split right, and you will be almost as well off in terms of electric bills as if you had a sync capable system, a parallel connection and a two way meter with a utility that pays cheap rates for that power. Letting that money go will cost less than using a gas generator for your backup power too, as big ones that can run a house are not cheap.
pluralistic