You are probably having a memory issue, l used to have 203 devices yesterday I deleted 4 Aqara FP1’s and a Sonoff MiniZB and all of my battery operated zigbee devices reconnected and have not dropped offline since. I onboarded the FP1’s but could not get all of them connected only 2, if I try to add the third I get a low memory message. So my current device count is 198 from API+ browser. I also had to delete the 3 drivers Wemo, Bose , and Smartthings Audio drivers in order to get the second FP1 to connect . With them showing in the driver list I would get the low memory warning.