Sigfox modem power supply

Hello Guys,

I have build a project with : - 1 Arduino nano - 1 Sigfox TD2018R modem - 1 LCD 2x16 I2C - 1 BMP280 barometric sensor

Everything is doing fine when I plug my USB cable to my computer. I want to make my projet autonomous, then I have a module with : - 1 Lipo rider pro - 1 LiPo battery 3.7v 2000mAh - 1 Solar panel 6V 3W

In that last configuration, the board is well powered, but it cannot initialize the Sigfox modem.

So I guess there is not enougth power but I'm not really sure about it... i'm a little bit newbee in power stuff !!

If someone can guide me what should I do to make my projet autonomous.

Kind Regards, Joseph