What's the easiest/least expensive way to convert our older Vantage Vue 6250 console to wireless? This version is not wireless and requires RJ45 from console to router.
That's a rather confusing question! A Vue console is already wireless in the usual terminology, ie the communication from sensors outside to console inside is wireless.
So I'm guessing you must mean the onward connection from console to eg PC. But since you specifically mention router then I'm guessing that you must have an older WeatherlinkIP logger installed in the console. Assuming so then the the simplest option is to replace the WeatherlinkIP logger by a WiFi Logger. Or buying a Weatherlink Live unit would be another option. You haven't mentioned what software or cloud platform you're using - that would have some relevance as to the best replacement.