If connections/files/stuff passes that is less than 1 network packet (about 1500 bytes - header--say 1460 give or take) then this is a sign that a piece of the network somehow has the wrong MTU size. I have seen network ports not get their MTU set to 1502 or 1504 and when this happens it causes the MTU on the network to be 2-4 bytes short and causes havoc. Routers have done similar things. I have seen network port restarts sometimes cause the MTU to be wrong. ping -s 1400 <target> and ping -s 2000 <target> if 2000 fails then raise the 1400 by 2 bytes at a time until it starts failing (or do a binary search for it, but it is going to be under 1500). Lower your main host interface's MTU by say 4 and retest, if that "fixes" it that is a sign that this is the issue. On Sat, Nov 11, 2023 at 4:08 PM <fedora@xxxxxxxxxxxxxx> wrote: > > Since the middle of the night on 7/Nov, uploading files with ssh is problematic. > > My SMTP server requires SSL/TLS security, and uploading files to the same site requires sftp. > So both run over ssh. > > I have a few scripts that run from cron and send me mail when required. > They also upload some files for other people and for me when I am away from home. > > Now here is the problem. Small files pass though just fine. Using sftp I measured > that files up to 1300 bytes upload, but anything larger hangs. Large mail is also blocked, > queued as seen in mailq: > (timeout writing message to xxxx.xxxx.net.au.: Connection timed) > > It seems that after some time (often hours) things resolve. > Rebooting the machine also allows the mail through. > > Scripts that upload larger files (using lftp) hang for hours. > > Now I tested the same from a laptop over 4G and it does not show any of these problems. > So it is probably not at the receiving end (I also asked them). > All they see is occasional timeouts on mail and ssh (from me). > > I cannot figure what can do this. Small files upload OK larger ones hang??? > > I said earlier "middle of the night" because I was not at my computer then and > nothing of note that I could see, but the problems started showing in the logs. > > There is still the possibility of my ISP fiddling with the modem remotely (in the > past they did it around this time). I am chasing them. > > One thing that can help now is a way to un-hang the uploads without having to reboot. > I do not know where to even look. > > Some details: > > The modem uses 4G for wireless internet. > > I used a laptop wired to my server, then wired to the modem, then connected to my WiFi ap > (which is wired to the modem) and all hang on large(ish) uploads. > > Only when I connected the laptop to my phone (as a WiFi ap) things worked well. > > BTW, one thing I did was disable ipv6 but the problem persists. > > -- > Eyal at Home (eyal@xxxxxxxxxxxxxx) > _______________________________________________ > users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx > To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx > Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ > List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines > List Archives: https://lists.fedoraproject.org/archives/list/users@xxxxxxxxxxxxxxxxxxxxxxx > Do not reply to spam, report it: https://pagure.io/fedora-infrastructure/new_issue _______________________________________________ users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@xxxxxxxxxxxxxxxxxxxxxxx Do not reply to spam, report it: https://pagure.io/fedora-infrastructure/new_issue
