Blynk nodemcu cannot connect to wifi with serial connection

Hi Everyone.
Just would like to ask if anybody else has experienced my case.
I recently bought a lolin nodemcu and used it to connect to hc12 via the serial pins.
Everything works and i’m able to see the values from the hc12 in the blynk app. However, on initial boot, I need to
first disconnect the hc12 from the serial pins, otherwise the nodemcu cannot connect to wifi. I tried to use other pins (GPIO13/15) but still got the same result. Has anyone seen this before?

Don’t use GPIO15.

More of a question for the ESP forums… for example…[0]=13