One of the options available in OpenVPN that can lead to a lot of confusion is
ifconfig-pool-persist. This directive tells the OpenVPN server to maintain a persistent list of IP addresses handed out to different clients. When a client reconnects at a later time, the previously-used address is reused. This is only one of three methods for assigning static addresses to an OpenVPN client. The other two methods are:
ifconfig-pushstatement in a client-connect script
ifconfig-pushstatement in a client-configuration file
Both of these take precedence over the entries found in the
ifconfig-pool-persist file. Experience has shown that it is often a good idea to temporarily disable this option when an OpenVPN ...