SSH port issue

Hi,
I used cenminmod to change the ssh port to 999 and it worked for a week but recently I have to stop the iptables to connect via ssh.
This happened to me on other vps too.
Even I used the Ip which used for installation (so already in the allow list) but no success.

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And the log:

Nov 16 05:19:01 XXX kernel: Firewall: *TCP_IN Blocked* IN=eth0 OUT= MAC=00:50:56:be:39:0a:00:17:5a:79:d2:56:08:00 SRC=XXXXXXXXXXXX DST=XXXXXXXXXXXX LEN=48 TOS=0x00 PREC=0x00 TTL=105 ID=1573 DF PROTO=TCP SPT=15809 DPT=999 WINDOW=8192 RES=0x00 SYN URGP=0