Consumer or business grade router that has a built in VPN client. On the consumer side you can often flash OpenWRT/DD WRT/PfSense to add a VPN client.

But for a more reliable setup you want a business-grade router which supports it natively.

Basically you have a router such as the Cisco [880] take care of the encryption and extends the corporate private network into the home office.

[880] http://www.cisco.com/c/en/us/support/routers/880-integrated-...

Just FTR, you can (almost?) just as easily use VyOS. It is open source and supports IPSEC site-to-site.