Blynk.begin() failure for GSM board

[Carlini2016]

Blynk library version: [1.3.2]
IDE: [Arduino]
IDE version: [2.3.2]
Board type: [ESP32 TTGO A7670]

I connect on GSM Network with sucess, the boad receive the IP from Vivo Network. The GSM/Internet is OK.

When I try to connect to the Blynk server using the command "Blynk.begin(auth, modem, apn, user, pass), the board somethimes connect with sucess and somethimes no.

When the board can not connect, the board enter in a loop " Connecting to blynk-cloud.com:80" and never more stop (no timeout) making It Impossible to do another action or execute another command.

Best regards

Thales