CSF limit problem

hallo i tried to limit the connections per IP
i show that there is the way with domain.com.conf with the limit_conn limit_per_ip 16;

and there is the the connection limit through csf
i do not know if these 2 ways are relevant or even if they are the same but the fact is that although i have used both it does not work.

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here is the results after running the /etc/csf/csftest.pl

Spoiler: result

Testing ip_tables/iptable_filter...OK
Testing ipt_LOG...OK
Testing ipt_multiport/xt_multiport...OK
Testing ipt_REJECT...OK
Testing ipt_state/xt_state...OK
Testing ipt_limit/xt_limit...OK
Testing ipt_recent...OK
Testing xt_connlimit...FAILED [Error: iptables: Invalid argument. Run `dmesg' fo r more information.] - Required for CONNLIMIT feature
Testing ipt_owner/xt_owner...OK
Testing iptable_nat/ipt_REDIRECT...OK
Testing iptable_nat/ipt_DNAT...OK

as you can see the xt_connlimit failed,how can i fix that or what else can be done

thank you