Connecting and running smoothly on mobile hotspot while rc=-2 on fiber broadband wifi router

[my-reminiscence]

I'm using WS2812FX, PubSubClient and ESP01 which is connecting and running smoothly on mobile hotspots getting while rc=-2 error when connecting to the fiber broadband wifi router. It is happening with WS2812FX only, not with other libraries like DHT11, AQI, etc. I think there's any configuration required either on firmware or router which I'm not able to find out.

Here's the things that I've already checked -

1. Client Id is unique, checked.
2. FQDN and IP Address, checked.
3. Power supply, checked.
4. client.loop(), checked.
5. Reconnect(), checked.