Synology VPN server limits the maximum number of concurent connections on DS216j with DSM 6.0

Question

In Synology DiskStation DS216j with DSM 6.0 in the settings of VPN server for PPTP, OpenVPN and L2TP, there is a line "Maximum connection number" with possible options just 3 or 5. According to Synology KnowledgeBase, its purpose is "to limit the number of concurrent VPN connections", probably with the intention of limiting the cpu usage. Is it possible to set this option to other (higher) values somehow?

Answer 1

Possible workaround is to edit configuration files over SSH

For PPTP edit the file /usr/syno/etc/packages/VPNCenter/pptp/accel-pppd.conf Change the line "tunnel=10.0.0.1-5" to "tunnel=10.0.0.1-10" - then the Maximum connection number will be set to 10.

For OpenVPN edit the file /usr/syno/etc/packages/VPNCenter/openvpn/openvpn.conf Adjust the line "Max-clients 5".

For L2TP edit /usr/syno/etc/packages/VPNCenter/l2tp/x12tpd.conf Change the line "ip range=10.2.0.1-5" to something like "ip range=10.2.0.1-10"

Finally restart NAS.

Keep in mind, that each encrypted VPN connection puts additional load on CPU, so keep the limit reasonable according to your model. Though with 1 GHz CPU in DS216j and 7 concurrent VPN users, I rarely see it go over 30%.