@JulioSilva 

Switches do not support VPN, which you need. You need some kind of IPSec VPN connection, which is supported by SMB routers usually. If you already have some routers on your sites, which don't support VPN, you need to change it. TP-Link has TL-R600VPN (the cheapest) and TL-ER6020/6120 (the best). You can configure IPSec VPN LAN-to-LAN between 2 sites and also configure PPTP/L2TP server for external users.

@Mitya what do you suggest and for a simple use of top 5 users at the same time?

Is it worth it the extra cost or the cheapest can handle it the same way for my case?

Thanks.

@JulioSilva 

It depends on your needs. TL-R600VPN can have 20 IPSec tunnels and 16 PPTP-tunnets the same time, so it should be OK for you. However, the main difference between these devices is IPSec Thoughput. It is only 13Mbps on R600VPN and about 100Mbps on ER6020/6120. I can say, that TL-ER6020/6120 is one of the fastest IPSec router on the market on such price. Yes, you suffer because lack of some functions, which you usually want to see on SMB router with such speed, but price, mmmm.... Very good choice for me. For my projects I usually need the same as you and chose ER6020 (it also has several WAN-ports), while TL-R600VPN I do not like exactly because on low IPSec throughput speed.