"Device is Offline" Error When Using GSM Connection via Advantech UR5i v2 Router

I am reaching out to seek assistance with an issue I am encountering in my Blynk setup. The system operates flawlessly when connected via my home Wi-Fi network; data are successfully sent to and received from the Blynk server. However, when using a customer’s GSM connection through an Advantech UR5i v2 Libratum Wi-Fi router, I face the following problem:

Data Transmission: Data from the device are correctly registered on the Blynk server.
Data Reception: When attempting to send data from Blynk to the device, an “device is offline” error message appears, and the data are not transmitted to the device.

Current Setup:

Device: esp32 wroom 32
Router: Advantech UR5i v2 Libratum Wi-Fi Router
Connection Type: GSM via Advantech UR5i v2 Libratum router
Blynk Library Version: 1.3.2

Many thanks