So, if the connection is being shut down on the server side, it's likely because of the TLS version mismatch. I thought it would be a simple solution just via updated software but was told (by peeps on Reddit, so it's likely to be total nonsense) that, although it can be updated, it won't run reliably on older hardware unless that hardware can also support newer OSs. Win7 and below (?) don't support it and MS won't provide updates with it and MacOS versions before Lion don't have it. I've heard you can also update OpenSSL by breaking the symlinks to the OS's install and get it working again but that's more hassle than I cared to put in.
Also, most of those old iPads are able to be jailbroken. You can update OpenSSL on them and probably get Spotify working again.