Possible to use Transparent Mode with 10+ modules and no addressing

Question

We have a network using 10+ S2C modules communicating randomly (sending ~200 byte records) to our host program on a PC using a XBee3 Xstick. All devices including the Xstick are in default transparent mode with no DH/DL addresses set on any device. No configuration changes are made other than CH (channel). Host PC is "always ON listening". Remote devices wake and send data randomly, sometimes simultaneously, and then return to sleep. Each record takes approx 1 sec to send. Each device may try to send as many as 30+ records at once. This network appears to be highly unstable, especially as the number of devices increases.
Btw, I did not design or build this network, but have been tasked with trying to understand how to make it work. Thanks.

Answer 1

Are you using Digi Mesh, 802.15.4 or Zigbee?

Answer 2

We are using 802.15.4. Our firmware does some "clear channel" testing, but at times multiple devices will request to send at the same time. We have legacy devices using the S1 module which seem to have a very hard time sharing the channel with the S2C's. Also, if we use the early S1 based Xstick, the range drops severly (likely the 1mW transmit power).