After messing about for the best part of two weeks with the Netgear kit I got fed up and ordered the Draytek 2830. When it arrived I had the job finished, VPN set up and running in two hours from start to finish and to make it even better the Draytek client software is a free download unlike the Netgear £150 for 5 licences.
Configuring VPN Load Balance using DrayTek Routers: 1194: Using the “Enable Ping to Keep IPsec Tunnel alive” option: 1129: VPN IPSec LAN to LAN Draytek 2830 & Netgear FVS336Gv3: 1126: VPN IPSec LAN to LAN Draytek 2925 & Billion router: 1116: Video – Configuring IPsec VPN Tunnel (Aggressive Mode) Between Two Vigor Routers: 1098 How to configure Draytek 2860 modem as bridge Jun 08, 2016 Draytek 2830 internet access - DrayTek Sep 10, 2012 DrayTek - Wikipedia
Also, consider a reset to factory defaults on the Draytek, you'd be amazed what this can sometimes fix. Unfortunately the Draytek 2850 is a little bit of an "odd one", they didn't produce them for very long.. I would definately contact Draytek UK support though if the above suggestions don't work, it is still considered a supported product.
Draytek Vigor 2830n-Plus - wireless router - DSL modem - 802.11a/b/g/n - desktop overview and full product specs on CNET.
ip - Draytek 2830, Multiple VLANS on Same Port - Server Fault
Aug 22, 2019 Draytek 2830 – Finishing Up | The Sysadmins Dec 04, 2011 DrayTek Vigor 2830 review | 30 facts and highlights DrayTek Vigor 2830 Universal Plug n Play (UPnP) is a set of networking protocols that permits networked devices, such as PCs, printers, internet gateways, Wi-Fi access points and mobile devices to find each other and exchange information on the network. DrayTek Australia – Your partner for reliable networking ADSL/VDSL Modem Routers Broadband Routers LTE Routers Network Switches Access Points Network Management VigorAP 1000C Tri-Band 802.11ac Wave 2 Access Point with Mesh Wi-Fi, 1 x GbE port, 1 x Gigabit PoE PD port and Dual-LAN