TCP Disconnect not happening


We are working in an embedded environment where we use two scenarios HTTP connection without SSL - Http client and HTTP connection with SSL - Https client . We have our own HTTP application & SSL stack which uses the underlying TCP-IP connection which is where we use Wiz W7500S2E-R1 module. Both the HTTP and SSL stack are proven application and they are working fine for years with our previous Modem. The TCP-IP connection and Data transfer to and fro works fine with both the scenarios. Once confirmed all the data transfer has been done, when the application tries to close the active TCP-IP connection by coming out of data mode (by sending +++ with a time gap of 1 sec each before and after sending) , the first scenario HTTP connection without SSL - Http client is working as expected .Here the Wiz module sends a FIN packet to the remote host to disconnect the active connection. But in the second scenario HTTP connection with SSL - Https client , the Wiz modem doesn’t sends a FIN packet to the remote host. The remote host disconnects the connection after certain timeout.

I tried with setting the inactive timer to 1 ms and setting the reconnect time to 55 secs after coming out of the data mode and later going back to data mode (AT+EXIT). Later i expect the Wiz modem disconnects the connection. I tested with two different HTTPs connection i.e different servers (as TCP client). The result is, in one of the case, the Wiz modem sends a RST packet to the remote host in ~6 secs after entering data mode. In other case, nothing happened and the connection ended by remote host on timeout.

Hope i gave a clear and detailed story. Please help.

Thanks in advance.

Please reply for my question as this is really IMPORTANT for my current work.


First, the Standard firmware of WIZ750 series not support HTTPS protocol.
Did you modified the firmware in order for you to use HTTPS?
Could you please attach the capture packet using wireshark?


Thanks for the reply. I am attaching the Wireshark log for the TCP-IP connection to HTTPS client.

Below are the main Modem configurations i did in WIZ modem here,

  1. Set DHCP mode - IP obtained is ‘’
  2. Local port - 5000
  3. Remote host -, Port - 443
  4. Setting as TCP client

In the Wireshark log, the modem has been powered on at “2020-03-10 11:12:50” and the connection has been started to establish at “2020-03-10 11:12:52” by sending a SYN packet to remote host.

Later sending all the data, the application tries to disconnect the modem by sending “+++” command to modem, expecting to send a FIN packet to remote host around “2020-03-10 11:14:55”. But nothing happened and later the remote host has disconnected the active connection by sending RST packet after ~2 mins timeout. (17.1 KB)

I apologize for the late response.
You’re right. If you send “+++” command to modem during TCP operation, it must be send the FIN Packet from module to PC.
I’m not the person in charge of the matter.I’ll let the person in charge know this problem.


  1. F/W version and capture of Configuration tool. (100.9 KB)

Attached the Configtool images.

Device type is W7500S2E-R1. The software version is 2.3.

Attached the Configtool (100.9 KB)


Device type is W7500S2E-R1. The software version is 2.3.

Attached the Configtool (100.9 KB)
Please update on any progress on this issue. awaiting for your reply.