losing internet connection after a few days after using opnsens

[Djazeiry]

hello guys , i'm new to opnsense and advanced networking , where i am i started by using opensens after insatlling it on a physical machine and made it as my DHCP Server , everything works fine for a few days and then suddenly i lose the internet connection on the network , my network  structure is explained on the joined image ,  my firewall configuration is by default didn't touch anything

network structure :

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