I tried every idea possible in all chains....
setting it on public ip, setting it on local bridges.
Yet, I see big packets.
I only want to change MSS for outgoing TCP connections, thus I cannot change the mtu of the pppoe-wan.Could IFB be the culprit somehow?
root@turris:~# iptables-save | grep TCPMSS
-A PREROUTING ! -s 192.168.0.0/16 -d publicip/32 -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A PREROUTING ! -s 192.168.0.0/16 -d 192.168.1.1/32 -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A PREROUTING ! -s 192.168.0.0/16 -d publicip/32 -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A PREROUTING -i pppoe-wan -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A INPUT -i pppoe-wan -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A INPUT ! -s 192.168.0.0/16 -d 192.168.0.0/16 -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A INPUT ! -s 192.168.0.0/16 -d publicip/32 -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A FORWARD ! -s 192.168.0.0/16 -d 192.168.0.0/16 -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A FORWARD ! -s 192.168.0.0/16 -d public/32 -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A FORWARD -o eth2 -p tcp -m tcp --tcp-flags SYN,RST SYN -m comment --comment "!fw3: Zone wan MTU fixing" -j TCPMSS --clamp-mss-to-pmtu
-A FORWARD -i eth2 -p tcp -m tcp --tcp-flags SYN,RST SYN -m comment --comment "!fw3: Zone wan MTU fixing" -j TCPMSS --clamp-mss-to-pmtu
-A FORWARD -o pppoe-wan -p tcp -m tcp --tcp-flags SYN,RST SYN -m comment --comment "!fw3: Zone wan MTU fixing" -j TCPMSS --clamp-mss-to-pmtu
-A FORWARD -i pppoe-wan -p tcp -m tcp --tcp-flags SYN,RST SYN -m comment --comment "!fw3: Zone wan MTU fixing" -j TCPMSS --clamp-mss-to-pmtu
-A FORWARD -i pppoe-wan -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A OUTPUT ! -s 192.168.0.0/16 -o br-lan -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A OUTPUT ! -s 192.168.0.0/16 -o wlan1 -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A OUTPUT ! -s 192.168.0.0/16 -o br-LANWIFI -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A POSTROUTING ! -s 192.168.0.0/16 -d publicip/32 -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A POSTROUTING ! -s 192.168.0.0/16 -d 192.168.0.0/16 -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -m owner --uid-owner 453 -j TCPMSS --set-mss 540
-A POSTROUTING ! -s 192.168.0.0/16 -o br-lan -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A POSTROUTING ! -s 192.168.0.0/16 -o wlan1 -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540
-A POSTROUTING ! -s 192.168.0.0/16 -o br-LANWIFI -p tcp -m tcp --tcp-flags FIN,SYN,RST SYN -j TCPMSS --set-mss 540