I have two 43" TCL Roku TVs that I bought at different times a few years apart. One of them still works with my ECP commands, while the other one doesn't and stopped working a week or two ago. I also have two more 43" TCL Roku TVs in my household that belong to a housemate that I could arrange some testing on as well, if more samples is helpful.
Here is the info from the About screen on each TV to help your engineers isolate the root cause for your customers:
---
Not Working TV:
TCL model: 43S435
Hardware ID: G109X
Serial number: available privately if needed
Software version: 12.5.5 - build 4174-CG
Device ID: available privately if needed
IP address: 192.168.187.109
---
Working TV:
TCL model: 43S403
Hardware ID: 7126X
Serial number: available privately if needed
Software version: 12.5.5 - build 4174-30
Device ID: available privately if needed
IP address: 192.168.187.71
---
Test setup for both samples: Tested from Elgato StreamDeck using two plugins - one called "API Request" and the other called "API Ninja". Both of these plugins were configured to send "http://<IP address>/keypress/PowerOn" and "http://<IP address>/keypress/PowerOff" ECP commands as an HTTP POST request. I also tested using PowerShell from Windows 11 Professional with these commands (results below each command):
Invoke-WebRequest -Method Post -Uri "http://192.168.187.109:8060/keypress/PowerOn"
--> Returned error: Invoke-WebRequest : The remote server returned an error: (401) Unauthorized.
Invoke-WebRequest -Method Post -Uri "http://192.168.187.109:8060/keypress/PowerOff"
--> Returned error: Invoke-WebRequest : The remote server returned an error: (401) Unauthorized.
Invoke-WebRequest -Method Post -Uri "http://192.168.187.71:8060/keypress/PowerOn"
--> Returned expected response (TV powered on) with StatusCode 200
Invoke-WebRequest -Method Post -Uri "http://192.168.187.71:8060/keypress/PowerOff"
--> Returned expected response (TV powered off) with StatusCode 200
The results were the same with all 4 tests from the StreamDecks using both plugins from both computers (a total of 24 tests, 12 per computer, 1 set of 4 tests with each method described from each computer) as the PowerShell results. These results indicate that the TV is receiving the requests but is not responding to them for an unidentified reason and returns a HTTP 401 Unauthorized error. For unrecognized commands, it returns a HTTP 404 Not Found error, as expected. I also tested all of these conditions from two different computers to rule out an issue on one computer - the results were identical from both computers in all test cases.
