Yo, Nully !!
Is the fabric leaking or is it seam leakage?
I've never heard or seen nylon fabric leaking.
My Cabelas Outback, 12X12 tent leaked copiouslyat the seams in deep snow during an Oct elk season a few years ago. I had waterproofed it with "Camp Dry and "Seam Sealer" very well.
I got a beeswax emergency candle out and drug it back & forth along the seams inside and out, worked great!!
.
No more leaks!
It's not a forever fix, but it works for a season.
Hnter