Forum Discussion

Retired_Member

Sep 14, 2020

Solved

Orbi RBR20 v2.5.1.16 IPv6 PPPoE missing TCPMSS

Orbi RBR20 firmware v2.5.1.16 WAN PPPoE IPv4+IPv6 - VDSL Provider - LiveTIM - Sao Paulo - Brazil IPv4, IPv6 and IPv6-PD (LAN) are aquired as expected I have no throuble in IPv4 services, eve...

CrimpOn
Sep 14, 2020
Retired_Member wrote:
Question
As I discovered this issue days after my 90 days support finished, I'm unable to report this bug through an official channel. How could I persist this soluction?
What seems to have worked in this situation is to send a private message to one of the forum moderators by clicking on their screen name, such as Dustin_V (the moderators have a capital "N" after their name). Moderators seem to have a mechanism to communicate with Netgear engineers and support staff.

Retired_Member

Sep 16, 2020

Let me register, the right comnand is

ip6tables -t mangle -I POSTROUTING -o ppp0 -p tcp -m tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu

PS: The command specified in the first post is missing mangle table.

CrimpOn

Guru - Experienced User

Sep 16, 2020

Please forgive my ignorance. Does this situation affect every ISP connection type?

i.e. both PPPoE and DHCP?

Retired_Member
Sep 16, 2020
CrimpOn wrote:
Please forgive my ignorance. Does this situation affect every ISP connection type?
i.e. both PPPoE and DHCP?
- Retired_Member
  Sep 16, 2020
  Once my ISP provides PPPoE only, I'm unable to try others
  - Retired_Member
    Sep 16, 2020
    MTU 1492, default for PPPoE, MSS adjusted to 1432 (-60 bytes)
    
    MTU 1452, MSS adjusted to 1392 (-60 bytes)
    
    Without ip6tables rule, MSS always is 1440, despite MTU value