pfSense doesnt access to my WAN

[macaruchi]

Hello!
I am new to using PfSense but not other FW's. I am having strange behavior as I cannot surf the internet on my network. When I try to ping the modem/inet from a client, it says General Failure, but if I ping the modem from pfSense, everything is correct. Sometimes it communicates but if it lasts a while without connecting when I try again, it no longer navigates or if it does, it does not do so with all the pages. My configuration is quite standard for these cases:
inet --> modem<--> pfSense --> LAN

but from the LAN I cannot reach the modem that is the router for that part, it is as if the NAT rule did not exist to be able to jump between networks but I checked it and it is installed by default. From my pfSense if I can get anywhere but not from the LAN I have already done everything until I did a new installation and the same thing happens, it works for a while and then the communication drops
I have tried with several client machines and the same thing happens, if I can, from these, reach PfSense through the LAN network, the web configuration, I can even ping any machine on the LAN from pfSense server
I have pfSense 2.6.0 installed

HELP