I have a user with a Lenovo P72 laptop running W10 Pro 1803.
When user is at home connected to Comcast wifi, he uses Sonicwall Global VPN to connect to office. Problem occurs when he disconnects from VPN, his wireless download speed drops into the kbps range. Tried IPCONFIG /flushdns, /release, and /renew to no avail. Only gets speed back after a reboot of system.
We thought this might be a result of VPN conflict, but the problem occurs in at least one other way we found. If user connects to a Verizon MiFi (mobile hotspot), he can use that to get internet. However, when he disconnects from MiFi, his wireless download speeds drop to unusable again.
IP addressing seems appropriate, just for some reason his download speed crashes to a halt when switching wireless connections.