Reddit mentions of GL.iNet GL-AR300M Mini VPN Travel Router, Wi-Fi Converter, OpenWrt Pre-Installed, Repeater Bridge, Hotspot, 300Mbps High Performance, 128MB Nand Flash, 128MB RAM, OpenVPN, Programmable IoT Gateway

I'm currently using a GL.iNet GL-AR300M. I'm using it in my hotel overseas right now through a captive portal. You can also run a VPN on the router itself. I believe it satisfies everything you're describing.

I've never deployed one for a corporate group, but I've had a great experience with GL.iNet equipment for personal use. At $40, it's tough to beat.

https://www.amazon.com/gp/product/B01I92T754

Seems like a simpler router with USB 3 Or even 2.0 would work fine for such minimal needs.

RT-AC68U running Merlin firmware or

open WRT device like https://www.amazon.com/GLI-GL-AR300M-Pre-installed-Performance-Programmable/dp/B01I92T754

I would run both if I had the budget, just to have some redundancy.

They are both Linux boxes with enough grunt for filesharing, openvpn, cloud backup etc. nothing you mentioned can't be done well with a 35 dollar Linux box. Only need the $200 AC router if you haven't upgraded to 5Ghz networking.

https://www.amazon.com/GL-iNet-GL-AR300M-Pre-installed-Performance-Programmable/dp/B01I92T754

I'm in love with this thing. OpenWRT, openVPN, easy to use interface, loads of configuration options. and cheaper than a pi+SD card. Similar performance to a pi though but for what it is its great.

Or try one of these

https://www.amazon.co.uk/d/Computers-Accessories/AR300M-router-300Mbps-OpenWrt-Repeater-OpenVPN-Falsh/B01I92T754/ref=sr_1_1?ie=UTF8&qid=1497645034&sr=8-1&keywords=gl-ar300m

I use a travel router, specifically the Gli.net AR300M
https://www.amazon.com/GL-iNet-GL-AR300M-Pre-installed-Performance-Programmable/dp/B01I92T754

It has two separate WiFi radio+antenna, one to connect to hotel WiFi, one for your devices.

1. You power it up, connect to it over WiFi (or Ethernet) with a browser and pick the hotel WiFi network
   
2. Then browse to neverssl.com
   
3. Usually the hotel's crappy portal will show up instead, login to that and then all your devices have internet
   
   It has OpenVPN preinstalled, so you can also use that to avoid the hotel from messing with your traffic.
   
   It runs off a standard USB port. I've used it on a plane to share wifi, powered off a battery bank or my laptop.

I have a gl inet router. This one specifically: https://www.amazon.com/dp/B01I92T754/ref=cm_sw_r_cp_apa_i_u-D3DbQRYJPEN

Pretty sure I got it for under $30 when I bought it.

You could get one of these pre loaded with OpenWRT

https://smile.amazon.com/GL-iNet-GL-AR300M-Pre-installed-Performance-Programmable/dp/B01I92T754/ref=sr_1_fkmr0_1?keywords=GL.iNET+sim+card&qid=1567713707&s=electronics&sr=1-1-fkmr0

https://smile.amazon.com/GL-iNet-GL-AR750S-Ext-pre-Installed-Cloudflare-Included/dp/B07GBXMBQF/ref=sr_1_fkmr1_1?keywords=GL.iNET+sim+card&qid=1567713707&s=electronics&sr=1-1-fkmr1

Then power it via a power bank. As large or as small as you want. They just run off micro usb 5v 1 amp connection.

https://smile.amazon.com/Anker-PowerCore-Ultra-Compact-High-Speed-Technology/dp/B0194WDVHI/ref=sr_1_3?keywords=power+bank&qid=1567713843&s=electronics&sr=1-3

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EDIT: You can also tether these to a cell phone if you need to. Quite flexible devices.

If you want a cheap option that gives you some other flexibility you could look at an inexpensive router with multiple LAN ports that supports AP Mode. That one device would act like a switch and an access point in one. Something like this should do it, as long as you don't mind updating the firmware and have only one device that needs to be wired. Or this one to get 3x gigabit wired ports rather than 2x 10/100 on the cheaper device.