The offer says which server made it.
The server identifies itself
The server identifier option carries the address of the server making this toy offer.
server option=54
The server id is four bytes
The server identifier length is 4 bytes, matching an IP version 4 address.
server id bytes=4
Read the server address
The server identifier is 192.168.1.1.
server=192.168.1.1
Summary
The offer-shaped message includes both the offered client address and the server identifier.
server option=54