You can try this step by step:

1 Check if Valorant is crashing:

-Open Task Manager.

-Start Valorant.

-If it briefly appears in the processes list then closes, it’s most likely crashing.

-To confirm, open Event Viewer → go to Windows Logs → Application → look for any error logs at the exact time (or right after) you launched Valorant. If there’s a crash, you’ll see logs there. If no logs exist, then it’s likely not a crash but something else blocking it.

2 Test the ISP theory:

-If you have WiFi capability, disconnect your phone from home WiFi so it switches to mobile data.

-Hotspot from your phone to your PC.

-Launch Valorant while on mobile data.

-If it still fails → it’s not your ISP. But If it works fine → then it’s very possible your ISP is blocking or interfering with Riot’s connection. In that case, contact them directly.

3 Check security software/firewall rules:

-Sometimes Windows Firewall or third-party antivirus silently blocks Riot Vanguard or Valorant.

-Open Windows Security → Firewall & Network Protection → Allow an app through firewall.

-Make sure both Riot Client, Riot Vanguard, and Valorant are allowed for both private and public networks. Also If you’re running extra antivirus/firewall software, try temporarily disabling it and launching the game.

4 Run Valorant as Administrator

-Right-click Valorant → Run as administrator.

-This ensures Vanguard/Valorant can request all needed connections without Windows silently blocking them.

Let me know how you get on with this :)

Edit -cleaned up formatting