Synology RT1900ac User Manual page 34

Can the VPN Server package work on my router if I use IPv6 connection?
If the router provides IPv6 connection, you can only use VPN Server as an OpenVPN server. The other types of
VPN (i.e. PPTP and L2TP/IPSec) are not supported under an IPv6 environment.
What can I do if I can't connect to the router via VPN connection?
Make sure you enable the VPN pass-through function and select the corresponding options of the VPN protocols
(PPTP, L2TP, IPSec) that you use.
Why does a message keeps popping up telling me I do not have a valid
certificate when I visit some HTTPS websites?
When you visit an HTTPS website, the website will continuously send a request to SRM for a valid certificate. If
the website or some of its elements is in the block list, SRM cannot answer the request with a valid certificate,
and the message will keep popping up.
To work around this issue (due to the HSTS concerns), you can continue to visit the website or add the website to
the allow list (at Network Center > Parental Control > Web-filter > Edit Allow List) so that the message will not
pop up again.
34 Chapter 14: FAQ