From 2015 till 2016 we installed OES2015 servers.

Now we see that the support will end 14 Jun 2017.

That is already very soon and we want support so we are planning an upgrade.

1) Should I install new ones and move disks

2) Upgrade the current ones (+ what is the best way to upgrade)

What are the experiences with upgrades?

Two servers we still have have iFolder. I know it gave some problems with the initial OES2015 install.
What do you think? Will it give issues again?

On an upgrade will we need to re-configure every part like AFP / CIFS / LDAP / DNS?