So I have VDSL as one of my WANs on my AX86U and I noticed that the router cannot be set to higher than 1492 MTU in the PPPoE WAN setting. I try to set it to 1500, but I get a message in the GUI that 1492 is the max. I tried to set it to 1500 through SSH, but it doesn't actually do anything and as soon as I reset the router, it goes back to 1492.
My modem is the Vigor 130 which supports MTU up to 1520 - I have set it to 1500 (in PPPoE passthrough mode). And my ISP supports baby jumbo frames, so it can do the full 1500. So the limitation appears to be the router, can it really not do 1500 MTU (i.e. 1508 - 8 PPPoE overhead)
My modem is the Vigor 130 which supports MTU up to 1520 - I have set it to 1500 (in PPPoE passthrough mode). And my ISP supports baby jumbo frames, so it can do the full 1500. So the limitation appears to be the router, can it really not do 1500 MTU (i.e. 1508 - 8 PPPoE overhead)