Two recent kernel upgrades seem to have both affected the Intel Corporation Wireless 7265 (rev 59) adapters on our systems in a manner which causes their network transfer rates to be reduced dramatically. File transfers which normally require a few minutes are now taking several hours. These systems are running the Debian testing distribution with the iwilwifi drivers from Debian's testing/contrib. The altered behavior came when the Debian linux-image version advanced to 4.15.*. I looked online for similar reports and didn't find anything that seemed directly applicably. I finally got lucky when I experimented with the net.ipv4.tcp_congestion_control setting. I understand that in version 4.15 of the kernel the default was changed from cubic to bbr. I used # sysctl net.ipv4.tcp_congestion_control=cubic to revert to the previous default on all of the systems. This has caused all of the systems to return to their normal file transfer speeds. Please let me know by direct reply (I'm not subscribed.) if I can supply more information. Best regards, JP
