While the TP-Link is no Cisco IOS, it's a wee bit more complicated than your typical NetGear/DLink/Linksys, isn't it? What's your experience with switches/routers?
So, after logging into the unit's webpage, you should be able to click on 'Quick Setup'. You can then try 'Auto Detect', but to be safe I would just select 'Static IP', the next page then should just ask you to enter your settings for said Static IP. Alternatively, if you click 'Network', and select WAN Connection Type 'Static IP' you can configure it all-manually.
SafeStream Gigabit Multi-WAN VPN Router MODEL: TL-R600VPN TL-R600VPN, TP-Link's SafeStream Gigabit Multi-WAN VPN Router, supports Gigabit Ethernet connections on both WAN and LAN ports which guarantee high-speed wired connectivity. What’s more, it integrates multiple VPN protocols, high-security and high-performance VPN capabilities. TP-Link SafeStream TL-R600VPN Gigabit Broadband Desktop VPN Router, 680M NAT throughput. What This Product Does? TL-R600VPN, TP-LINK's SafeStream Gigabit Broadband VPN Router, supports Gigabit Ethernet connections on both WAN and LAN ports which guarantee high-speed wired connectivity.
The LAN ports are only that, so when you click on DHCP and select the IP address ranges that you'd like to use, DHCP will be broadcast through all four of them.
Tl R600vpn Setup
When you say 'NO Security', basic firewall settings are enabled by default, which you probably would want to keep unless this box has a specific function. Most everything else you're thinking of needs to be configured and enabled, so you should be good. No load balancing on this box, since it doesn't support Dual-WAN...
Tp Link Tl R600vpn Manual
Clear as Mud? TP-Link had an actual web simulator of that model, but I think it's been taken down since a newer model has replaced the R600. I tried to look it up anyway, but their web page seems REALLY sluggish and unresponsive.