You have 4K equipment with a VGA port. But does it actually do 4K when using VGA or does it just downscale? I haven't ever seen any VGA cable which can go above 2048×1536, and that's also the maximum wiki mentions:
When I set my mom up, in 2003 or so, I gave her one of mine 21" Integraph monitors. I was a bit jealous when I realized her computer was able to do accelerated 24 bpp 2048×1536 on that gorgeous (and back-breaking) screen. My laptop at the time could drive on external screen at 1024x768 and that was it. :-(
Ah, so it 'pays' with a low refresh rate. That makes sense.
That said, my point was that 4K computer monitors are rare (despite some communities of enthusiasts), and nearly everything currently in use has a VGA port.
VGA is an analog signal, so there is no theoretical limit, and the degradation is graceful --- edges of individual pixels will start looking blurry as you get closer to the physical limitations, but a recognisable image continues to appear.
I also have a 4k tv on my wall. It also has VGA.