By default your devices needs the following upload capacity per device to work at peak efficiency:
At least 250 kbits per second (or 0.25 Mbps) for 4G connections
At least 500 kbits per second (or 0.5 Mbps) for LAN/Wi-Fi connections
Testing a LAN/Wi-Fi connection
From a PC/laptop on the same network as your device, you can visit a third party speed test service (such as Speedtest) to test your network. This should should calculate the available download and upload capacity of your network:
The important value here is the Upload speed, which should exceed the values above.
Note: Your internet capacity can change depending on time of day, and other devices on your network.
Testing a 4G connection
This is more challenging as:
If your SIM card was supplied with your device you will probably be unable to try the SIM card in another device as it may be locked to your device.
Using your SIM card in another device to run a speed test will probably give different results given the modem and antenna are different.
If you are local to your device you can use Local access mode to check your device's signal strength.