Is there a reason that the TP-Link VR1600v modem-router has an IP address pool limited to 100 devices (192.168.1.100 to 192.168.1.199)?
Is it possible to change the range to include all possible IP addresses (192.168.1.2 to 192.168.1.255)?
Can I manually assign IP addresses outside of the set pool?
I don't know why they chose that particular range. You can set the pool to be from 192.168.1.2 to dot 254.
The pool is used by the router to assign a dynamic address to a device. You can make an address reservation so a device is always the same ip address; it might be running a server function. The reservation would normally be from outside the pool but the router may let you allocate an address within the pool. While allowing 253 ip addresses, there may be a limit on the number of devices which can be connected at one time.