21.02 rc4: mt7530 mdio-bus:1f lan1: Link is Down, Link is Up

I am having the similar issue on ubnt x-SPF; The wan port keeps flapping up and down and causes not being able to complete PPPoE.

  • The dsl modem is SR501 with 100mbp port
at Feb 19 22:20:26 2022 daemon.notice netifd: Network device 'eth4' link is up
Sat Feb 19 22:20:26 2022 daemon.notice netifd: Interface 'dsl_wan' has link connectivity
Sat Feb 19 22:20:26 2022 daemon.notice netifd: Interface 'dsl_wan' is setting up now
Sat Feb 19 22:20:26 2022 daemon.notice netifd: Interface 'wan_modem' has link connectivity
Sat Feb 19 22:20:26 2022 daemon.notice netifd: Interface 'wan_modem' is setting up now
Sat Feb 19 22:20:26 2022 daemon.notice netifd: Interface 'wan_modem' is now up
Sat Feb 19 22:20:26 2022 daemon.err insmod: module is already loaded - slhc
Sat Feb 19 22:20:26 2022 daemon.err insmod: module is already loaded - ppp_generic
Sat Feb 19 22:20:26 2022 daemon.err insmod: module is already loaded - pppox
Sat Feb 19 22:20:26 2022 daemon.err insmod: module is already loaded - pppoe
Sat Feb 19 22:20:26 2022 daemon.info pppd[7568]: Plugin rp-pppoe.so loaded.
Sat Feb 19 22:20:26 2022 daemon.info pppd[7568]: RP-PPPoE plugin version 3.8p compiled against pppd 2.4.8
Sat Feb 19 22:20:26 2022 daemon.notice pppd[7568]: pppd 2.4.8 started by root, uid 0
Sat Feb 19 22:20:26 2022 daemon.debug pppd[7568]: Send PPPOE Discovery V1T1 PADI session 0x0 length 12
Sat Feb 19 22:20:26 2022 daemon.debug pppd[7568]:  dst ff:ff:ff:ff:ff:ff  src xx:xx:xx:xx;xx
Sat Feb 19 22:20:26 2022 daemon.debug pppd[7568]:  [service-name] [host-uniq  90 1d 00 00]
Sat Feb 19 22:20:27 2022 daemon.notice netifd: Network device 'eth4' link is down
Sat Feb 19 22:20:27 2022 daemon.notice netifd: Interface 'dsl_wan' has link connectivity loss
Sat Feb 19 22:20:27 2022 daemon.notice netifd: Interface 'wan_modem' has link connectivity loss
Sat Feb 19 22:20:27 2022 daemon.notice netifd: Interface 'wan_modem' is now down
Sat Feb 19 22:20:27 2022 kern.info kernel: [  146.505755] mt7530 mdio-bus:1f eth4: Link is Down
Sat Feb 19 22:20:27 2022 daemon.err pppd[7568]: select (waitForPADO): Interrupted system call
Sat Feb 19 22:20:27 2022 daemon.warn pppd[7568]: Timeout waiting for PADO packets
Sat Feb 19 22:20:27 2022 daemon.err pppd[7568]: Unable to complete PPPoE Discovery

I also tried to disable eee, and had no difference;

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The interesting parts are that

  • This issue seems only happening when using PPPoE; where if DHCP is used, the port can stay on;
  • The workaround is to put a switch ( I am using a gigabit one) in between; then I can connect every single time;
--> This is from kernel log:
Port flapping:
[  202.825891] mt7530 mdio-bus:1f eth4: Link is Up - 100Mbps/Full - flow control off
[  203.849763] mt7530 mdio-bus:1f eth4: Link is Down

Workaround that works
[  219.209984] mt7530 mdio-bus:1f eth4: Link is Up - 1Gbps/Full - flow control rx/tx
[  219.427297] pppoe-dsl_wan: renamed from ppp0
  • The original edge os doesn't have this issue