Zabbix Proxy cannot send list of active checks to endpoints

[AccidentalAdmin79]

Greetings:

I wish to use a Zabbix server on prem, with a Zabbix proxy in Azure to monitor our Citrix environment (which is housed in Azure). At any given moment, we could have 50 or so VM's up and managed by Citrix though all VM's are ephemeral. The VM content and settings are 99% dictated by various "gold images." The gold images have Zabbix Agent2 installed (they are Windows machines) with confs as follows (in relevant part):

##### Passive checks related

### Option: Server
#    List of comma delimited IP addresses, optionally in CIDR notation, or DNS names of Zabbix servers and Zabbix proxies.
#    Incoming connections will be accepted only from the hosts listed here.
#    If IPv6 support is enabled then '127.0.0.1', '::127.0.0.1', '::ffff:127.0.0.1' are treated equally
#    and '::/0' will allow any IPv4 or IPv6 address.
#    '0.0.0.0/0' can be used to allow any IPv4 address.
#    Example: Server=127.0.0.1,192.168.1.0/24,::1,2001:db8::/32,zabbix.example.com
#
# Mandatory: yes, if StartAgents is not explicitly set to 0
# Default:
# Server=

Server=192.168.128.110

### Option: ListenPort
#    Agent will listen on this port for connections from the server.
#
# Mandatory: no
# Range: 1024-32767
# Default:
# ListenPort=10050


### Option: ListenIP
#    List of comma delimited IP addresses that the agent should listen on.
#    First IP address is sent to Zabbix server if connecting to it to retrieve list of active checks.
#
# Mandatory: no
# Default:
ListenIP=0.0.0.0


### Option: StatusPort
#    Agent will listen on this port for HTTP status requests.
#
# Mandatory: no
# Range: 1024-32767
# Default:
# StatusPort=


##### Active checks related

### Option: ServerActive
#    Zabbix server/proxy address or cluster configuration to get active checks from.
#    Server/proxy address is IP address or DNS name and optional port separated by colon.
#    Cluster configuration is one or more server addresses separated by semicolon.
#    Multiple Zabbix servers/clusters and Zabbix proxies can be specified, separated by comma.
#    More than one Zabbix proxy should not be specified from each Zabbix server/cluster.
#    If Zabbix proxy is specified then Zabbix server/cluster for that proxy should not be specified.
#    Multiple comma-delimited addresses can be provided to use several independent Zabbix servers in parallel. Spaces are allowed.
#    If port is not specified, default port is used.
#    IPv6 addresses must be enclosed in square brackets if port for that host is specified.
#    If port is not specified, square brackets for IPv6 addresses are optional.
#    If this parameter is not specified, active checks are disabled.
#    Example for Zabbix proxy:
#        ServerActive=127.0.0.1:10051
#    Example for multiple servers:
#        ServerActive=127.0.0.1:20051,zabbix.domain,[::1]:30051,::1,[12fc::1]
#    Example for high availability:
#        ServerActive=zabbix.cluster.node1;zabbix.cluster.node2:20051;zabbix.cluster.node3
#    Example for high availability with two clusters and one server:
#        ServerActive=zabbix.cluster.node1;zabbix.cluster.node2:20051,zabbix.cluster2.node1;zabbix.cluster2.node2,zabbix.domain
#
# Mandatory: no
# Default:
# ServerActive=

ServerActive=10.100.1.4:10051

### Option: Hostname
#    List of comma delimited unique, case sensitive hostnames.
#    Required for active checks and must match hostnames as configured on the server.
#    Value is acquired from HostnameItem if undefined.
#
# Mandatory: no
# Default:
# Hostname=

#Hostname=

### Option: HostnameItem
#    Item used for generating Hostname if it is undefined. Ignored if Hostname is defined.
#    Does not support UserParameters or aliases.
#
# Mandatory: no
# Default:
HostnameItem=system.hostname​

My zabbix proxy config is follows in relevant part:

############ GENERAL PARAMETERS #################

### Option: ProxyMode
#    Proxy operating mode.
#    0 - proxy in the active mode
#    1 - proxy in the passive mode
#
# Mandatory: no
# Default:
ProxyMode=0

### Option: Server
#    If ProxyMode is set to active mode:
#        IP address or DNS name (address:port) or cluster (address:port;address2:port) of Zabbix server to get configuration data from and send data to.
#        If port is not specified, default port is used.
#        Cluster nodes need to be separated by semicolon.
#    If ProxyMode is set to passive mode:
#        List of comma delimited IP addresses, optionally in CIDR notation, or DNS names of Zabbix server.
#        Incoming connections will be accepted only from the addresses listed here.
#        If IPv6 support is enabled then '127.0.0.1', '::127.0.0.1', '::ffff:127.0.0.1' are treated equally
#        and '::/0' will allow any IPv4 or IPv6 address.
#        '0.0.0.0/0' can be used to allow any IPv4 address.
#        Example: Server=127.0.0.1,192.168.1.0/24,::1,2001:db8::/32,zabbix.example.com
#
# Mandatory: yes
# Default:
# Server=

Server=192.168.128.110:10051

### Option: Hostname
#    Unique, case sensitive Proxy name. Make sure the Proxy name is known to the server!
#    Value is acquired from HostnameItem if undefined.
#
# Mandatory: no
# Default:
# Hostname=

Hostname=DD-0823-ZbxPrxy-01

### Option: HostnameItem
#    Item used for generating Hostname if it is undefined.
#    Ignored if Hostname is defined.
#
# Mandatory: no
# Default:
#HostnameItem=system.hostname

### Option: ListenPort
#    Listen port for trapper.
#
# Mandatory: no
# Range: 1024-32767
# Default:
ListenPort=10051

### Option: SourceIP
#    Source IP address for outgoing connections.
#
# Mandatory: no
# Default:
# SourceIP=​

Discovery rules look like this:



Discovery Action looks like:

Errors on the endpoint (DD-ITDESKTOP-01):

2023/09/14 16:04:20.275787 [101] no active checks on server [10.100.1.4:10051]: host [DD-ITDESKTOP-01] not found
2023/09/14 16:04:25.280944 [101] no active checks on server [10.100.1.4:10051]: host [DD-ITDESKTOP-01] not found
2023/09/14 16:04:31.272762 [101] no active checks on server [10.100.1.4:10051]: host [DD-ITDESKTOP-01] not found
2023/09/14 16:04:37.270420 [101] no active checks on server [10.100.1.4:10051]: host [DD-ITDESKTOP-01] not found
2023/09/14 16:04:42.277554 [101] no active checks on server [10.100.1.4:10051]: host [DD-ITDESKTOP-01] not found​

etc.

Errors on the proxy (10.100.1.4):

815468:20230914:155742.092 cannot send list of active checks to "10.3.3.6": host [DDCTXPROD02] not found                                                        
815466:20230914:155742.185 cannot send list of active checks to "10.3.3.26": host [DDCTXPROD17] not found                                                      
815468:20230914:155742.241 cannot send list of active checks to "10.3.3.5": host [DDCTXPROD26] not found

etc.

Any suggestions? Thank you!

[cyber]

Your Server and ServerActive in hosts config should point to same endpoint... if using proxy, then both should be pointing to proxy...