You've said in the title you wanted a VPN, haven't you? Software encryption requires a lot of CPU power, look at the encryption throughput of different models (in fact, it is so bad for software encrypton that it even not published in the data sheets of the models without hardware encryption). Also bear in mind that the CPU power you don't waste for encryption remains available for routing etc.
Out of the plastic boxes, only hEX (Gr3, I hope no older revisions are delivered any more) and hAP ac² have CPUs with hardware-supported encryption, and it has a tremendous impact on the overall throughput. The number of ports is the same for both, none has PoE-out (grrr). As compared to the hEX, hAP ac² has slightly better encryption throughput at AES-256, it has a quad-core CPU while hEX has a dual-core one. It has the wireless part for $10 add-on to the list price, and it does not have a micro-SD slot as compared to hEX.
Anything else with hardware encryption is much more expensive, excluded the cAP ac which, for the same list price as hAP ac², has the same CPU/wireless chip but only two Ethernet ports.
So yes, you can also take a cAP ac, hang it to the ceiling where wireless coverage is needed, and bring to it one uplink cable and bring back one cable to a dumb switch in the location where you need to connect the PCs and the server which you'll have there anyway (5 PCs and a server need 6 ports while both hAP ac² and hEX have only 4 ports left once you connect the uplink). The overall cost depends how much a meter of cable including installation costs in your part of the world.
The idea to use a cAP ac as the only machine has limitations of course, namely you cannot place the PCs and the server into different subnets with a firewall between them, which is what you should do to protect the server from an eventually infected PC.