Redis Cache on AWS vs Azure

Hi,
I have 2 web servers , 1 db server deployed with nop on AWS. I use AWS Redis cache for nopCaching  and it works fine. Unfortunately Microsoft.Wed.Redis.RedisSessionState is not working with nopCommerce on AWS , as described here: https://www.nopcommerce.com/boards/t/43898/redis-noconnection-available-on-logout.aspx

As a test I setup Redis cache on Azure and it is working fine. The only difference from the web.config perspective is lack of password setup on AWS, while there is an access key for Redis on Azure.

Any idea why this could be happening?

Do you believe it males sense at all to host the site at AWS and the Redis Cache at Azure? Aren't you effectively killing the advantage of having a fast distributed caching in one cloud provider's region?

Either move all to AWS or Azure, but don't spread across Cloud Providers