Yes, I tested with both 14 and 14.5 iOS. Everything works. The problem can be with the device itself or with a cell operator.
If you have access to your Triumph-2 from your computer, I recommend to use different connection variant - your iPhone will be access point and your Triumph-2 will connect to it with WiFi.
Please on your iPhone goto Settings and select Personal HotSpot
Then see your device WiFi name and password
Then connect your Triumph-2 to your computer with NetView&Modem, go to Settings | Networking | WLAN
And set - DHCP Client - on, DHCP Server - off, Access Point SSID - name of your iPhone WiFi, AP Mode - wpa, WPA Passphrase - your wifi password
Set Status Mode - on
Click green check mark to apply. Receiver will restart.
You should see that connected is done with such icon on your iPhone -
And in the NetView&Modem you can see your receiver IP Address -
Run JMT. Type the IP in IP address field. And it will connect to.
Port and Password can be check also with NetView in the Server page: