Port closed between TCP connection interval

[jyijyi]

does this help by disabling eDRX mode?

WP7702 TCP no answer after 2s

Also you can have a look here: I wonder if this is related to RRC_IDLE, also you can bring it back to RRC CONNECTED by just doing a simple TCP transfer such as keep-alive packet. In addition, you can try if there is improvement by disabling edrx feature by AT+CEDRXS=0