"AC Power Sensor" not detected & "Mobile Sensor & Gateway" password issue after firmware update

I connected a "Mobile Sensor & Gateway" on my PoE network and I have access to the web server (firmware release is 5.20).
When I connect a "AC Power Sensor" as "Probe 1" on the "Mobile Sensor & Gateway, it is switched on but it is not detected by the "Mobile Sensor & Gateway" (oled display and web server). After documentation review, I do not see how to add this sensor on the web server. I tried this:
- Factory resetting on the "Mobile Sensor & Gateway" (firmware release down to 3.20) then a firmware upgrade with the download "FACTORY_HWver5_Fw_Mobile_Release_5.20.bin" (firmware release is 5.20).
-> I lose the web access (id & password unknown!) so I won’t be able to perform the additional settings
-> The "AC Power Sensor" is always not detected on the oled display.
Need help, please!

As per specs the AC Current Sensor does not (yet) work with the Mobile Sensorgateway.

Thanks for the reply. As evoked in my first message, I performed a firmware upgrade for my "Mobile Sensor & Gateway" with the download "FACTORY_HWver5_Fw_Mobile_Release_5.20.bin". "admin/admin" doesn't work ! Any help would be much appreciated.

Just reset the settings of your gateway so it would return to the original username and password.

I already reseted the settings of my "Mobile Sensor & Gateway" and I returned to the original username and password but in firmware release 3.20 and not in 5.20 as I received the equipment. I have not all required settings, especially for the sms configuration. Thus, I would be happy if you could provide the admin-id/pwd for this firmware upgrade. Thank you in advance for your reply.

once you are done doing the reset then just update it over back to the latest firmware

https://serverscheck.com/support/firmware.asp

i done that again but i have always the same problem: "admin/admin" does no longer work and i have the error message "401 Unauthorized: Password required"...

if your settings on version 3.2 firmware work the username and password should not change, however if you have updated to the latest version 5.2, perform a settings reset by pressing the reset button while the unit is ON for 15 seconds after the restart try to access it again via admin/admin. if you are not able to access it on 5.2 even after a settings reset then either you must have not reset it properly or the unit is set for repair.

I followed this recommendation: "While the Gateway has power (connected to a power adapter or PoE), press the reset button for 5 seconds until the LED blinks. This will just reset the settings including Username and Password.
The firmware would still be the same." and all is perfect now. The equipment remains with the last firmware release in 5.20 and "admin/admin" is working fine.