Connection to server fail

Hi, I’m doing a project with Arduino and can visualize values ​​in Blynk. About 3 weeks ago I made a simple example in which I visualized a temperature and humidity probe. My team has been arduino mega 2560 + GSM900 SHIELD. For 2 weeks he has worked correctly. 5 days ago I wanted to try an arduino one r3 with the same shield, but I have a problem. Arduino connects and disconnects every 1-2 minutes, and when it takes about 4-5h it keeps trying to connect and I stop receiving data to blynk. It no longer reconnects correctly. 2 days ago I returned to Arduino mega 2560 with the same sketch I had and now has the same connection failure with the same conditions as before. What’s going on?