For all Tosibox 600 and 175 Nodes LAN IP has been fixed from the launch. For Lock 500 ja Lock 150 it was a changing value from predefined list prior to release v4.6.10. Starting with firmware release v4.6.10 with release date 2022-12-07 all Locks and Nodes have fixed LAN IP.
It is recommended to change the LAN IP according to network topology specification and document it. LAN IP is user configurable on the Lock management user interface.
See How to change LAN IP address space settings
In case multiple VPN tunnel need to be kept and you prefer to use fixed LAN IP, NAT can be enabled alternatively.
See How to set up 1:1 NAT on Lock (Lock & Client mode)