Zabbix server is not running in the frontend

[nsh15]

I have Zabbix 4.0.3 running in Ubuntu server

zabbix-server service is showing as running but the frontend shows its not with a warning (Zabbix server is not running)
Zabbix agent on the server itself is giving errors , but I am not sure if the agent is related to the server status


For Zabbix-agent on the server
I added the IP of the server to the config file with and wihtout 127.0.0.1 , yet the same error remain
I verified the iptables allows 10050-10052 range
I tested with ServerActive=127.0.0.1 and without ,but the same error
In zabbix, I tried zabbix server host with 127.0.0.1 and its real ip , still it shows red with errors in the log

failed to accept an incoming connection: connection from "<my ip>" rejected, allowed hosts: "127.0.0.1"

For FrontEnd
I read that frontend checks the zabbix status using ps , but it returns a number and not zero

ps -ef|grep zabbix_server|grep -v grep|wc -l
30
ps -ax|grep zabbix_server|grep -v grep|wc -l
30

This is my zabbix-service

● zabbix-server.service - Zabbix Server
Loaded: loaded (/lib/systemd/system/zabbix-server.service; enabled; vendor preset: enabled)
Active: active (running) since Thu 2020-10-29 13:20:49 UTC; 1h 21min ago
Process: 1936 ExecStop=/bin/kill -SIGTERM $MAINPID (code=exited, status=0/SUCCESS)
Process: 1941 ExecStart=/usr/sbin/zabbix_server -c $CONFFILE (code=exited, status=0/SUCCESS)
Main PID: 1944 (zabbix_server)
CGroup: /system.slice/zabbix-server.service
├─1944 /usr/sbin/zabbix_server -c /etc/zabbix/zabbix_server.conf
├─1945 /usr/sbin/zabbix_server: configuration syncer [synced configuration in 0.060627 sec, idle 60 sec
├─1946 /usr/sbin/zabbix_server: alerter #1 started
├─1947 /usr/sbin/zabbix_server: alerter #2 started
├─1948 /usr/sbin/zabbix_server: alerter #3 started
├─1949 /usr/sbin/zabbix_server: housekeeper [deleted 29471 hist/trends, 0 items/triggers, 0 events, 0 sessions,
├─1950 /usr/sbin/zabbix_server: timer #1 [updated 0 hosts, suppressed 0 events in 0.000350 sec, idle 59 sec
├─1951 /usr/sbin/zabbix_server: http poller #1 [got 0 values in 0.000306 sec, idle 5 sec
├─1952 /usr/sbin/zabbix_server: discoverer #1 [processed 0 rules in 0.000375 sec, idle 60 sec
├─1953 /usr/sbin/zabbix_server: history syncer #1 [processed 0 values, 0 triggers in 0.000009 sec, idle 1 sec
├─1954 /usr/sbin/zabbix_server: history syncer #2 [processed 0 values, 0 triggers in 0.000019 sec, idle 1 sec
├─1955 /usr/sbin/zabbix_server: history syncer #3 [processed 10 values, 3 triggers in 0.001180 sec, idle 1 sec
├─1956 /usr/sbin/zabbix_server: history syncer #4 [processed 0 values, 0 triggers in 0.000235 sec, idle 1 sec
├─1957 /usr/sbin/zabbix_server: escalator #1 [processed 0 escalations in 0.000798 sec, idle 3 sec
├─1958 /usr/sbin/zabbix_server: java poller #1 [got 0 values in 0.000010 sec, idle 5 sec
├─1959 /usr/sbin/zabbix_server: java poller #2 [got 0 values in 0.000017 sec, idle 5 sec
├─1960 /usr/sbin/zabbix_server: proxy poller #1 [exchanged data with 0 proxies in 0.000011 sec, idle 5 sec
├─1961 /usr/sbin/zabbix_server: self-monitoring [processed data in 0.000026 sec, idle 1 sec
├─1962 /usr/sbin/zabbix_server: task manager [processed 0 task(s) in 0.000281 sec, idle 5 sec
├─1963 /usr/sbin/zabbix_server: poller #1 [got 4 values in 0.003440 sec, idle 1 sec

# netstat -na | grep 10051
tcp 0 0 <zabbix IP>:10051 0.0.0.0:* LISTEN
tcp 85 0 <zabbix IP>:10051 <Server 1 IP>:32774 CLOSE_WAIT
tcp 0 0 <zabbix IP>:10051 <Server 2 IP>:37920 SYN_RECV

Zabbix Server logs

1944:20201029:132049.066 Starting Zabbix Server. Zabbix 4.0.3 (revision 87993).
1944:20201029:132049.066 ****** Enabled features ******
1944:20201029:132049.066 SNMP monitoring: YES
1944:20201029:132049.066 IPMI monitoring: YES
1944:20201029:132049.067 Web monitoring: YES
1944:20201029:132049.067 VMware monitoring: YES
1944:20201029:132049.067 SMTP authentication: YES
1944:20201029:132049.067 Jabber notifications: YES
1944:20201029:132049.067 Ez Texting notifications: YES
1944:20201029:132049.067 ODBC: YES
1944:20201029:132049.067 SSH2 support: YES
1944:20201029:132049.067 IPv6 support: YES
1944:20201029:132049.067 TLS support: YES
1944:20201029:132049.067 ******************************
1944:20201029:132049.067 using configuration file: /etc/zabbix/zabbix_server.conf
1944:20201029:132049.071 current database version (mandatory/optional): 04000000/04000003
1944:20201029:132049.071 required mandatory version: 04000000
1944:20201029:132049.143 server #0 started [main process]
1945:20201029:132049.144 server #1 started [configuration syncer #1]
1946:20201029:132049.144 server #2 started [alerter #1]
1947:20201029:132049.144 server #3 started [alerter #2]
1948:20201029:132049.145 server #4 started [alerter #3]
1949:20201029:132049.145 server #5 started [housekeeper #1]
1950:20201029:132049.145 server #6 started [timer #1]
1951:20201029:132049.145 server #7 started [http poller #1]
1952:20201029:132049.146 server #8 started [discoverer #1]
1957:20201029:132049.154 server #13 started [escalator #1]
1959:20201029:132049.154 server #15 started [java poller #2]
1956:20201029:132049.154 server #12 started [history syncer #4]
1958:20201029:132049.154 server #14 started [java poller #1]
1960:20201029:132049.156 server #16 started [proxy poller #1]
1955:20201029:132049.157 server #11 started [history syncer #3]
1961:20201029:132049.157 server #17 started [self-monitoring #1]
1962:20201029:132049.157 server #18 started [task manager #1]
1963:20201029:132049.158 server #19 started [poller #1]
1954:20201029:132049.159 server #10 started [history syncer #2]
1964:20201029:132049.159 server #20 started [poller #2]
1965:20201029:132049.163 server #21 started [unreachable poller #1]
1953:20201029:132049.165 server #9 started [history syncer #1]
1966:20201029:132049.166 server #22 started [trapper #1]
1969:20201029:132049.166 server #25 started [alert manager #1]
1970:20201029:132049.166 server #26 started [preprocessing manager #1]
1968:20201029:132049.168 server #24 started [icmp pinger #1]
1967:20201029:132049.169 server #23 started [trapper #2]
1977:20201029:132050.004 server #29 started [preprocessing worker #3]
1971:20201029:132050.081 server #27 started [preprocessing worker #1]
1972:20201029:132050.081 server #28 started [preprocessing worker #2]
1964:20201029:132407.085 Zabbix agent item "agent.ping" on host "<my zabbix server name>" failed: first network error, wait for 15 seconds
1965:20201029:132507.572 temporarily disabling Zabbix agent checks on host "<my zabbix server name>": host unavailable
1965:20201029:134107.910 enabling Zabbix agent checks on host "<my zabbix server name>": host became available
1964:20201029:134458.522 Zabbix agent item "system.cpu.util[,guest]" on host "<my zabbix server name>" failed: first network error, wait for 15 seconds
1965:20201029:134552.987 temporarily disabling Zabbix agent checks on host "<my zabbix server name>": host unavailable
1949:20201029:135052.287 executing housekeeper
1949:20201029:135053.248 housekeeper [deleted 29471 hist/trends, 0 items/triggers, 0 events, 2 problems, 0 sessions, 0 alarms, 0 audit items in 0.959945 sec, idle for 1 hour(s)]
1949:20201029:145059.019 executing housekeeper
1949:20201029:145059.678 housekeeper [deleted 21431 hist/trends, 0 items/triggers, 0 events, 0 problems, 0 sessions, 0 alarms, 0 audit items in 0.658334 sec, idle for 1 hour(s)]


Thanks

[NilsA]

Can you post your iptables / agent logfile? Also try increasing the debug levels of your agent and server to check for errors.
Have you checked /etc/zabbix/web/zabbix.conf.php?