PPoE MTU problem sv 2.1 2.2

PPoE MTU problem. On SM in Point-to-Point Protocol over Ethernet (PPPoE) MTU set to 1492 (maximum), MSS Clamping is enabled. Ethetnet MTU is 1500. Software Version: 2.2
Sites like YouTube, Fasebook, twitter are not working. Any suggestions ?

Do you problems accessing any website or only a few of them?

only few of them