Why here default mtu/mru are 1460, when i got always 1480? And you saying its default.
https://wiki.mikrotik.com/wiki/Manual:Interface/PPPoE
PPPoE is standard 1492 and that results in a minimal MTU of 1460 for normal packets as written. Now there are baby-jumbo frames and my PPPoE is 1500 which is resulting in 1472 to be pingable without defragmenting.
Your ISP has to support this.
You mean that I can see only maximum mtu, which is 1480 with IP header? And minimal is 1460 with IP + TCP, which is only theoretical and doesn’t written in interface?
No, PPPoE does not use an IP header. It has a couple of options, which make the header length variable, so the MTU/MRU is not really fixed.
MikroTik use a default MTU/MRU of 1480 so there is room for all possible PPPoE options, but when you just use it without options you can set the MTU/MRU to 1492.
(and indeed when the ISP supports it you can use MTU 1500)
MTU/MRU is different from TCP MSS! TCP MSS is MTU/MRU - IP header size - TCP header size. This means TCP MSS is usually 40 or 44 less than MTU/MRU.
I see. Support, maybe you should change default MTU/MRU in wiki on 1480? https://wiki.mikrotik.com/wiki/Manual:Interface/PPPoE#Properties
Up.
Come on! When you want to contact support use mail. And it is sunday.
Furthermore this is a very unimportant issue. You can set the MTU to the value you like.
I know, but these 1460 mtu in description so bad looking 
So you require immediate attention during the weekend? On the ignore list you go…
No-no, it’s okay. I’ll just wait for monday
P.S.: I can’t go in ingnore list of whoever
If you create PPPoE client on router, you would see that default value isn’t 1460 or 1480, its auto. Why such a big deal? Auto would work even better then fixed value, and assuming you are leaving it @ default value, you do not care about it ( you do not have any specific requirement setting it this way or other).
Yeah, but when you choose auto it uses 1480 where 1492 would be more optimal. So manually setting it is better when you know the actual limit.
Anyway, there is no issue at all, the guy was just freaking out over a small error in the documentation (and bumping his topic during the weekend to have that fixed).
Relax, I’m just expert network engineer and love MikroTik routers
No, no there was no anger intended Its all good. And one more info, while i was working for biggest ISP here in Serbia, on one IX ( i’m not sure if it’s fair to write ASN ) , MTU on their side was set to 1480. You can imagine how L1 tech support was happy with 500.000 ADSL users calling
1480 is OK.
Using NTT’s environment in Japan, the MTU / MRU is 1454.
How do I change the MTU of the PPPoE Client? It doesn’t allow me to do it, it appears in gray and I can’t modify it.
Change the Max MTU and Max MRU on the “General” tab and the “Actual MTU” will follow that (unless you have set an impossible value).
I did it but on my PC for eth1 it still shows me a MTU of 1480: C
Max MTU and MRU apply in 1492: http://prntscr.com/prp17k
I lose packages the same way. http://prntscr.com/prp0tu