My dell external monitor show only 1024x728 resolution

I have Dell XPS 9570 4k laptop and Dell 2417DG 2k monitor. It work fine till date. But sudden my dell external monitor show max 1024x728 resolution max.

I have update BIOS, and all other driver but no luck. 

I try following test.

1. My XPS laptop with Dell 2417DG monitor show only 1024x728 resolution

2. My XPS laptop with other Dell 2417DG monitor it works fine for 2k resolution.

3. Alianware Laptop with Dell 2417DG (Prolematic Monitor) it works fine for 2k resolution.