First of all, I was trying to redeem a code for a game for xbox with turkey IP and it didn’t work. I thought that it was a problem with the only turkey IP’s but when I tried to access the redeem code website with a argentinian IP it was didn’t work too. It is a problem with Microsoft website or with the VPN?
I believe that Microsoft is trying to block or black list some VPN apps like VPN.lat, tunnel bear, and urban VPN.
I have been able to redeem with VPN.lat some days, because the devs of the app, I believe reset or change the ip addresses of the servers.
The one VPN that hasn’t given me any issues at the moment is Hola VPN, it is free but limited.
You just have to redeem the keys fast, anytime that you use it, so you don’t spend all of your time limit.
Keep in mind, that it resets the time after a day, if you use all of the time limit that the app gives you, if I’m not mistaken.
You are very welcome 
Thanks for the answer!
Thank you so much! Was having issues redeeming a code and couldn’t get a refund. I’ve tried a ton of free VPNs and this is the first one that worked immediately.