Make sure IPSEC service is running: type services.msc to your Start menu search box and run as administrator, then locate the IPsec policy service and double click on it to make changes and see the status
Change the Local Security Policy: type secpol.msc to your Start menu search box and run as administrator. Click the arrow next to Local Policies to expand its contents. Click to select the folder called Security Options. On the right hand side of the Local Security Policy, locate and double-click on Network security: LAN Manager authentication level. In the drop-down list, select "Send LM & NTLM - use NTMLv2 session security if negotiated". Click OK. On the right hand side of the Local Security Policy, locate and double-click on: "Network security: Minimum session security for NTML SSP based (including secure RPC) clients". Uncheck "Require 128-bit encryption". Click OK. Close Local Security Policy. Reboot pc.
Customize IPSEC settings: type windows firewall and advanced security to your Start menu search box and run as administrator. Action -> Properties -> IPsec Settings -> Select Customize for IPsec defaults -> Select Advanced in Data protection -> tick the box Require encryption for all connection security rules ....
Newer Dell laptops have a piece of software called "SmartByte" I found this piece of software was blocking our access to our VPN. Once I disabled this software I was able to successfully log in to the VPN. To fix the issue launch the "SmartByte" software from the Start menu. There is an on off toggle, turn off "SmartByte" and you are able to connect. You are able to uninstall the software and it does no harm to the system.
This software is installed by default on all Dell laptop systems since about June of 2017. I have not tested this with any desktop models.