Topic: IoT Hub ports 443 vs. 8883 TLS connection handling differences

Hi there,

I'm currently successfully testing Azure IoT Hub using the HTTPS API, but want to migrate to MQTT. Establishing a TLS connection on port 443 works well (using TLSv1.1, which is hand-shaked properly), but I'm unable to connect to port 8883, since my client immediately reports a closed connection. I have routed my traffic through my PC so that I could try to inspect what is going on and have come up with two Wireshark screen captures (which I can't post as my account isn't verified, on the 443 port connection it clearly reports the TLSv1.1 successful HS, while on port 8883 it's just TCP packets). My suspicion is that the IoT Hub treats traffic on the two ports differently and that it may only allow TLSv1.2 (which my client doesn't support) on 8883. Is this correct? Is there any way that I can force my IoT Hub to accept the lower version?. Do you have any advice on how I could actually troubleshoot the handshake on the IoT Hub side (no way to do it on the client side)? I am currently using the AT+ commands on an ESP-01 module (Latest firmware: AT version:  3 2018 12:00:06)/SDK version:2.2.0(f28eaf2)/compile time:Feb  6 2018 14:36:23/Bin version(Wroom 02):1.6.0).

Please help.

I did not find the right solution from the internet.

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