Linksys MaxMTU PPPoE bug

Discussion in 'HyperWRT Firmware' started by Glynne, Aug 12, 2004.

  1. Glynne

    Glynne Guest

    Dear Avenger20;

    Great job on the new firmware. There is a bug in Linksys's code however. If you get a chance in the next version please investigate this issue.

    Best I can figure those using PPPoE (like myself) on DSL will start having browsing problems IF you leave the MaxMTU set to AUTO or 1492. If lowered to 1490 it appears to fix the problem. I found a site that said there is a 0.8% improvement in protocol use if you use 1454 instead. Seems to have to do with PPPoE overhead plus ATM breaking the packets down to like 537 bytes. I digress.

    Anyway, this problem did not exist before the 2.4.03 official release. After it it does. Changes I noticed were the AUTO option stays on now when set. On previous versions when PPPoE and AUTO were selected it would put 1492 into the form and place it in manual. Why just setting MANUAL and 1492 does not work in 2.4.03-04 and HyperWRT 1.2-1.3 is beyond my understanding. Could it have to do with the new features added by Linksys (port triggering?)?

    I hope this info helps. I suspect you don't use PPPoE or DSL for your connection so this may be hard to test and verify. Let me know if I may help. I can repeat the problem within 30mins. of use.

    Thanks again for your work.
  2. Avenger20

    Avenger20 Network Guru Member

    Thx, that would be great, If you PM me your email address I will let you know if I have a bugfix to test it :wink:
  3. Esquire

    Esquire Mesquire Staff Member Member

    What kind of browsing problems can I be expecting?

    My WRT54G is set to AUTO for MaxMTU and, as in the past, 1492 as the value.
  4. Avenger20

    Avenger20 Network Guru Member

    Websites not opening anymore, msn messenger not connecting anymore...

    But this bug is only when you have dsl connection, they need 1492 as MTU and not 1500.
  5. Esquire

    Esquire Mesquire Staff Member Member

    Thanks. My router defaults to 1492, so I guess I'm ok :p
  6. Esquire

    Esquire Mesquire Staff Member Member


    I just came across a Windows MTU problem while trying to get my router to work with v1.3, and I don't know if this is related to the browsing problems discussed earlier.

    One of my wireless notebooks was having problems going to certain sites - very slow and sometimes to a crawl, and funny enough mostly happened to everything and anything to do with This Windows certainly had a huge dislike for connecting with its creator. Jokes aside, all other clients, wired or wireless, didn't exhibit this problem. I tested my connection using my ISP's test site and it was in tip top shape, and the wireless connection appears to be steady and solid with the HyperWRT firmware, so I concluded there was a problem with this notebook.

    I looked in the Registry and found that the MTU DWORD value was missing - I added it previously but somehow it has been removed. I recreated the DWORD entry, set it to 1492 (same as the router and rest of the network), rebooted, and BINGO!, back to normal.
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