I'm using vxWorks 5.5 and I'm trying to increase MTU for PPP link.

It works fine with MTU up to 2900 bytes. As soon as I set MTU to 3000 or
bigger receiver side fails to receive packet correctly. pppstatShow
reports that only 1307 bytes received and packet is rejected due to bad
fcs.

Does anyone have any ideas?
Thanks in advandce.