Orbi RBR20 v2.6.1.36, bug in IPv6 over PPPoE WAN remains.

On set 14th 20 I reported a bug on IPv6 over PPPoE WAN connection cause by wrong TCPMSS / MTU afecting my Orbi RBR20 v2.5.1.16, it cause and some insights about how to fix it. On that time the same bug were present on RBR50/RBR50 v2 running v2.5.1.16 and days after in v2.5.2.4 launched on set 17th 20.

Since then Netgear released RBR20 v2.6.1.36 (oct 7th 20) and RBR50/RBR50 v2 v2.6.1.40 (oct 27th 20), but unfortunatly they implemented fix only for RBR50/RBR50 v2 model and didn't care about RBR20.

RBR20 owners, I'm very disapointed with Netgear support behavior, but how could we ask to support team "save us" too ?

Fix implemented on RBR50/RBR50 v2 firmware v2.6.1.40 in /etc/net6conf/6service

diff ./_RBR20-V2.6.1.36.img.extracted/squashfs-root/etc/net6conf/6service ./_RBR50-V2.6.1.40.img.extracted/squashfs-root/etc/net6conf/6service
43a44,66
> 	
> 	wan_type=`$CONFIG get wan_proto`
> 	if [ "x$wan_type" = "xpppoe" ]; then
> 		wan_mtu=`$CONFIG get wan_pppoe_mtu`
> 	elif [ "x$wan_type" = "xl2tp" ]; then 
> 		wan_mtu=`$CONFIG get wan_l2tp_mtu`
> 	elif [ "x$wan_type" = "xpptp" ]; then
> 		wan_mtu=`$CONFIG get wan_pptp_mtu`
> 	elif [ "x$wan_type" = "xmulpppoe1" ]; then
> 		wan_mtu=`$CONFIG get wan_mulpppoe_mtu`
> 	else
> 		if [ "x$w6_type" = "xpppoe" ];then
> 			dhcp_mtu=`$CONFIG get wan_dhcp_mtu`
> 			wan_mtu=$(($dhcp_mtu-8))
> 		else
> 			wan_mtu=`$CONFIG get wan_dhcp_mtu`
> 		fi
> 	fi
> 
> 	#for 6to4 and 6rd, the header still have ipv4  
> 	if [ "x$w6_type" = "x6d" -o "x$w6_type" = "x6to4" ];then
> 		wan_mtu=$(($wan_mtu - 20))
> 	fi
54a78
> 	printf '\tAdvLinkMTU %s;\n' "$wan_mtu"

Dustin_V 
Blanca_O 

PS:

binwalk was used to unpack firmware images.