The strange story of accessing certain websites.

[w0w]

@Gertjan
It is not HE, it is my ISP PPPoE dual stack now. For the HE I have used MTU only, set to 1472, MSS left empty.

[frelanhardware]

Check for ISP issues on WAN1 by testing with an alternative DNS server or contact the ISP to resolve potential routing issues, and ensure your pfSense and network settings are correctly configured.