IPs are mapped via static (1:1) NAT as follows:
192.168.1.157 -> 172.18.88.169
192.168.1.158 -> 172.18.88.170
192.168.1.170 -> 172.18.88.171
192.168.1.172 -> 172.18.88.172
192.168.1.173 -> 172.18.88.173
The rest of the 192.168.1.0/24 range is mapped to 172.18.91.11 (Bridge's WAN Address) via IP Masquerade.