Existing passive proxy goes offline when adding new passive proxy

[sagarkhushalani]

We have 8 existing Zabbix proxies:

* 6 active proxies (Let's say A1-A6)
* 2 passive proxies, because of datacenter and firewall restrictions (P1 and P2)

They work as expected. Performance is good, no issues as they are. Great.

I need to add 2 more proxies (let's say P3 and P4), for 2 new regions. Due to firewall/datacenter restrictions, they must be passive.
I have a firewall request pending, so I know they will be offline/unreachable until that is completed, but that's ok.

Here's the issue:
When I add P3 and P4 (offline/unreachable as expected), P1 and P2 also go offline. As soon as I take P3 and P4 out of the Zabbix configuration (deleting them from the UI), P1 and P2 come back online (it takes about a minute).
They are entirely different machines, with different (fixed) IP addresses (different /24 subnets) and different A records, so I can't figure out why one set would affect the other.
None of the active proxies are affected by this in any way.

All passive proxy configuration files have the right "Server", "SourceIP" and "ListenIP" values set. When adding the proxies, I've tried using A records as well as IP addresses for the new proxie (P3 and P4) - no difference.

Thoughts/ideas?

# 0 = Active, 1 = Passive
ProxyMode=1

# Networking
Server=zabbix-server-address
Hostname=zabbix-proxy-p1
HostnameItem=system.hostname
ListenPort=10051
SourceIP=<proxy-ip>
ListenIP=<proxy-ip>

# System
LogType=console
DebugLevel=3

# Remote commands
EnableRemoteCommands=1
LogRemoteCommands=1

# Process
SocketDir=/var/run/zabbix

# Database
DBHost=127.0.0.1
DBName=zabbix_proxy
DBUser=zabbix
DBPassword=<dbpassword>
DBPort=13306

# Frequencies
HeartbeatFrequency=60
ConfigFrequency=360
DataSenderFrequency=30

# Pollers
StartPollers=100
StartPollersUnreachable=25
StartTrappers=25
StartHTTPPollers=10

# Cache
CacheSize=2G
HistoryCacheSize=1G
HistoryIndexCacheSize=1G

# External Utilities
FpingLocation=/usr/sbin/fping
Fping6Location=/usr/sbin/fping6

[cyber]

Hostname=zabbix-proxy-p1
I hope you just forgot to replace number here in example with something like pX.

[sagarkhushalani]

Hostname=zabbix-proxy-p1
I hope you just forgot to replace number here in example with something like pX.

Oops, sorry yes! The proxy name in the config should have been pX for the example config. It is correct in the real configuration files for each proxy,

[sagarkhushalani]

Also, in the logs, even with debug level logging on, all I see is something like

proxy <zabbix-proxy-p1> went offline.
proxy <zabbix-proxy-p2> went offline.
...
proxy <zabbix-proxy-p1> went online.
proxy <zabbix-proxy-p2> went online.