Since I'm having trouble with L2TP VPN, I decided to open HTTPS on the WAN temporarily so that I could access the Web Interface. It worked for a while, however, unfortunately, now I am seeing this instead from Google Chrome:
SSL connection error
ERR_SSL_PROTOCOL_ERROR
I've disabled and enabled HTTPS from the Device Access page, reverted back to the original certificate, etc. SSH, for the record, continues to work without a problem.
Cheers,
Kyle