Hello,
150 Mbps is bandwidth in absolutely ideal conditions disregarding any real world conditions, like network congestion, or even communication time between devices in reality throughput for RUT240 reaches up to 70Mbps
As for comparison with Mobile phone it is not like comparing equivalent devices since RUT240 uses CAT 4 LTE modem (with theoretical maximum bandwidth of 150Mbps), of course it depends on model but lets say iPhoneX uses CAT 12 LTE Module (with bandwidth of 600Mbps) Samsung Galaxy S10 uses CAT 20 LTE module (with bandwidth of 2 Gbps) and featuring functions like Carrier Aggregation so it is natural for them to have much greater throughput.
All that considered, and keeping in mind that there still is some interference, network congestion, and packet losses 50Mbps download speed for RUT240 is really reasonable.
Best regards,
Vidas.