Trivial Steps to reproduce:
Break the network between the Zabbix Server and the Zabbix Proxy for several hours, then restore network connection.
Proxy conf:
Server=10.2.1.81;10.2.1.82 .. DataSenderFrequency=1 .. ProxyBufferMode=hybrid ProxyConfigFrequency=5 ProxyMemoryBufferSize=10M ProxyOfflineBuffer=12 .. StatsAllowedIP=127.0.0.1,192.168.1.76 ..
Server conf:
SourceIP=10.2.1.81 .. CacheUpdateFrequency=5 .. StartProxyPollers=2 ProxyConfigFrequency=5 .. HANodeName=zabbix-01.exa.com NodeAddress=10.2.1.81
Result:
Zabbix Server log:
6890:20250612:043231.570 sending configuration data to proxy "zabbix-proxy-01.ex.com" at "192.168.1.76", datalen 17564, bytes 3579 with compression ratio 4.9 6989:20250612:073320.906 Proxy "zabbix-proxy-01.ex.com" changed state from online to offline 6989:20250612:121427.929 Proxy "zabbix-proxy-01.ex.com" changed state from offline to online 6817:20250612:141630.944 reloading configuration on proxy "zabbix-proxy-01.ex.com"
Many lines like this: 6864:20250612:144441.302 received id:25897580 is less than last id:26002109
Zabbix Proxy log:
903148:20250612:043231.600 received configuration data from server at "10.2.1.81", datalen 17564 ... 903156:20250612:121409.962 Still unable to connect... 903156:20250612:121426.547 Connection restored. 903148:20250612:121430.967 Connection restored. ... 903156:20250612:145534.907 zbx_setproctitle() title:'data sender [sent 6 values in 0.225718 sec, sending data]' ... 903148:20250612:145658.159 received configuration data from server at "10.217.197.81", datalen 36 ...903168:20250612:145936.271 zbx_setproctitle() title:'history syncer #1 [processed 22 values in 0.000674 sec, idle 1 sec]' ... 903177:20250612:150041.931 zbx_setproctitle() title:'self-monitoring [processed data in 0.000810 sec, idle 1 sec]'
zabbix[proxy,\{HOST.HOST},delay] item and trigger: 
but at the same time:
That is, somehow the proxy and the server exchange information, but it seems that the server does not accept this data.
As a result, there is no new data from hosts behind this proxy.
Expected:
The connection between Zabbix Server and Zabbix Proxy should be restored, old data from the proxy cache and new data should arrive again.
