Sophos XG 550 : Swap memory reached 99% exceeding the threshold of 95%

Hi

Today our internet connection get intermittent disconnected and checked the log found these several lines :

SWAP memory Usage reached 99%  exceeding the threshold of 95%.

Our system using 2 Sophos XG-550 using HA, both the primary and auxiliary using the same firmware XG550 (SFOS 17.5.8 MR-8.HF062020.1). When we restart the primary the internet connection went normal again.

result of disk space usage:

XG550_RL02_SFOS 17.5.8 MR-8.HF062020.1# df -h
Filesystem Size Used Available Use% Mounted on
rootfs 301.6M 58.1M 223.5M 21% /
df: /newroot: No such file or directory
df: /newroot/dev: No such file or directory
df: /newrootrw: No such file or directory
none 301.6M 58.1M 223.5M 21% /
none 11.7G 68.0K 11.7G 0% /dev
none 11.7G 15.5M 11.7G 0% /tmp
none 11.7G 14.6M 11.7G 0% /dev/shm
/dev/conf 385.4M 77.9M 307.5M 20% /conf
/dev/content 41.9G 449.2M 41.5G 1% /content
/dev/var 373.4G 95.8G 277.7G 26% /var

Please help regarding the intermittent issue and error log about the swap memory usage, any help will be greatly appreciated