Required IP addresses for TCP Retransmission requests for FLEX data can be checked on the screen of Router Configuration Sheet of arrowface with IP addresses that allocated by TSE (User LAN) for each user and the Mains User Code.
Available addresses among IP addresses that allocated by TSE are 16 host addresses.

For FLEX Standard: xxx.xxx.xxx. from 160 to 175 (16-host addresses).
For FLEX Full: xxx.xxx.xxx. from 176 to 191 (16-host addresses).

Available IP addresses can also be checked from arrowface.
Please refer to arrowface > Contract&Config > arrownet > Router - Common Config Sheet (PDF).