Does the ESP chip manufacturing date matter?

[kirillandy]

Hi all! So I'm dealing with an issue with ESP8266EX chips that I can't really understand, and as far as I can tell, the problem does NOT lie with the esp8266 Arduino SDK. After several tests, I have a suspicion that it has something to do with the manufacturing date of the ESP chip, but I have no way to explain it and I was wondering if anyone had a similar experience.

I've got a project which has worked reliably for years now. It utilizes softAP + STA mode. Basically, it

• launches softAP upon setup,
• waits for my app to transmit router data via TCP,
• connects to the router and returns a result via the still open softAP TCP connection,
• disables softAP.
  And this project has so far worked like a charm on dozens of ESP8266EX chips... until now. I have a chip that simply refuses to play nice and softAP is painfully unreliable. The ONLY significant difference I can find is that all my other chips were made in 2020. This one was made in Q2 of 2018 (week 15).

This is what happens:
(Just to decrease the number of possible factors, I try to connect to softAP via Windows' own Wi-Fi Manager, not my own Windows application.)

• For the newer chips, this is never a problem, I connect and receive an IP address and the connection stays stable. Disconnecting and connecting back are also no problem. Jump back and forth all you like.
  My own application communicates with these chips with no hiccups, it's all been debugged over the years. I pass router data, wait for the chip to connect and inform me, and then locate it in my router's network as described above.

• For the older chip, the first connection is OK, but it takes suspiciously longer. Then, if I disconnect, I have trouble reconnecting, with Windows Event Viewer usually citing Reason Code 0x2800B WLAN_REASON_CODE_NETWORK_NOT_AVAILABLE (link to MSDN provided with a description of possible (unhelpful) causes).
  If I use my app to attempt to carry out my softAP exchange above in that one rare instance when I manage to connect to softAP, softAP connectivity drops when I send the chip the router data for it to use. Every. Single. Time.

The question is: do manufacturing dates matter? Because there is literally no other difference I can pin down. The software used is the same. The chips are the same. Only difference is the date code and main die info on the chips themselves. I don't suppose this is a correct question to ask, but I'm having trouble finding any other words or causes: was there any important revision made to the ESP8266EX between 2018 and 2020 that altered how it behaved in softAP mode?