Easiest way to restrict access via IP is to use different subnets. put the PC you want to exclude into one subnet, and everything else into the other. Use subnet mask to allow everything other than the i-series access to both subnets, but restrict i-series access to only the main one.
eg. put everything except excluded pc into subnet xxx.xxx.10.xxx, put excluded PC into xxx.xxx.11.xxx, IP range for all PC’s including the excluded one should be
IP xxx.xxx.10.0 MASK 255.255.254.0
IP range for i-series should be
IP xxx.xxx.10.0 MASK 255.255.255.0
i-series will not then talk to xxx.xxx.11.xxx IP range.