EX3700 Speed drops after VPN disconnect

After connecting thru a VPN to one of my remote sites and the disconnecting, my network speeds drop dramatically.  Before connecting, I see network download speeds of 4-6 Mbps (using Measurement Lab M-Lab speed test).  After disconnecting and terminating the VPN connection, my speeds drop to 1-2 Mbps (or slower).  Re-booting the EX3700 restores the normal speeds.

Environment:  Using Verizon 4G LTE router for cellular connection, then EX3700 as range extender to my Windows 10 Pro system.

Note that I do not need to reboot the Verizon router or my computer - just the EX3700.

Any idea why/how rebooting the EX3700 fixes the speed problems?