@tmlysek 

Putting DD-WRT or any other third party firmware on a router is always a risk, after all third party firmware is basically just a hack. I have used DD-WRT on an old Linksys "G" router many years ago which worked very well. Today, I would be very reluctant to do so.  There are bad actors out there that add code to third to the party firmware and release it. That may be one reason for the conflicting info.

I would think most VPNs would be supported on this router either by OPENVPN or PPTP. If it will not work, consider a different VPN or router.

If you do it, have a recovery plan or at least know a router that can replace the A7 which will run your selected VPN if it does not work.

If it is a free VPN service, ask yourself, why is it free?

I think you misunderstood the question/ I have a A7v5 router that I want to flash with the proper dd-wrt software. Supposedly it's compatible. Wiki says do a 30-30-30, someone else says don't. Wiki says use the router data base. Peakock says don;t trust it. When I put the router info into the search field, I get two builds. One standard and one upgrade. I don;t know which one to choose or if I should even trust either one of them. Everyone says make sure you have the exact build or you might brick the router. I don;t really want to do that so I am asking if anyone knows exactly which one to use and where to get it. Is that even possible? Please save the generic risk warning. 

@tmlysek 

I suspect these quesstions would be better off asked in the DD-WRT forum? Either a developer or someone who did this could  answer you. Better chance to find someone who did do it there than here as if they did do it, they'd probably not be here?