How to fix this HyperVM 2.1.0 BETA error:

__error_no_socket_connect_to_server
It suddenly started appearing in WHMCS and in HyperVM

One thing to try, add server IP address in: HyperVM / Server (it is an tab) / Information / FQDN Hostname (field)

If not accessible, check network connection (netstat -np) if its somehow not exhausted?

Make sure /etc/hosts contains server IP and fqdn hostname on one line.

Login server via SSH and check iptables firewall on the server:

# iptables -L INPUT -n --line-numbers

Chain INPUT (policy ACCEPT)
num target prot opt source destination
1 DROP all -- 127.0.0.1 0.0.0.0/0
2 DROP all -- someblockedip 0.0.0.0/0
above output 127.0.0.1 rule is suspicious and appears to instruct firewall to DROP (block) localhost connections?

That line has prefix "1" as a first rule in the chain. So if i want to remove that rule 1, i first backup all firewall rules:

# iptables-save > /root/iptables.rules.backup

then remove 127.0.0.1 blocking rule, its on line 1, so i do:

# iptables -D INPUT 1

then i restarted HyperVM service by command:

# /script/restart

then HyperVM started working/connecting

i was suggested to add this iptable rule also:

# iptables -I INPUT -i lo -j ACCEPT

to save changes (get them applied after reboot), i did:

# /etc/init.d/iptables save

final iptables output:
Chain INPUT (policy ACCEPT)
num target prot opt source destination
1 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
2 DROP all -- someblockedip 0.0.0.0/0
Anyone please have ideas or experience with this issue causes/fixes? Thank you