Use the iperf3 command to test network speeds.

• iperf3 -s to start in server mode
• iperf3 -c 192.168.1.10 -t 20 to test server on ip address 192.168.1.10 for 20 tries.
• iperf3 -c 192.168.1.1 -t7 -b 2.5G -u 6001
• iperf3 -c 192.168.1.1 -t7 -R -b 2.5G -u 6001

• A Complete Guide to iperf3 Network Throughput Testing
• iperf Docs