Turns out that my left ureter was so compressed by my swollen lymph nodes that they couldn’t install the stent.
Same problem on the right side, too.
Only one solution: Bilateral Nephrostomy.
Good news: They were able to prevent further kidney damage.
Released after three days.
Bad news: Now I have two tubes penetrating my back and kidneys so that urine can drain into rubber bags strapped to my legs.