I know the subject has been brought up before here, but I just thought I'd point it out to whomever needs to know.
Sonicwall just released a beta 5.9.0 firmware and a specific KB article on configuring it to work with HE.
https://www.sonicwall.com/us/en/support/2213.html?fuzeurl=https://www.fuzeqna.com/sonicwallkb/ext/kbdetail.aspx?kbid=10214