Great your s6 is working now with Roon. However, setting it to a static IP is not really solving the problem on your LAN.
I suspect that when the S6 was using DHCP (as it ought to be) to obtain an IP address the router was allocating an IP to it but some other device was already using it.
It is most likely that the other device is using a static IP address which is within the DHCP IP pool range that the router is allocating from.
I would suggest installing a network scanner App such as Fing and use it to identify all the LAN connected devices so you can check for any offending addresses. Once that is dealt with it should be possible to revert your Galaxy S6 back to requesting its IP via DHCP (as their should not be an IP conflict anymore).
If you have any devices using static IP addresses, then do double check they are on the right subnet but outside the DHCP pool range, otherwise is only a matter of time until there are more IP address conflicts between DHCP and static IPs.
Personally I avoid static IPs on my home network … for hardwired devices like a server or a NAS etc. I set and reserve their IP using the DHCP IP allocation tables in the router. This way the device still requests via DHCP and the router always assigns it the same address. (The IP is constant and DHCP server manages them).
Hope that helps.
PS sometimes under abnormal conditions routers may get confused and forget what addresses they have dynamically allocated, when you have time it I’d suggest rebooting the router and then all the LAN connected devices.