6.5.0 Firmware upgrade causes network access issues

Bumping this thread, I believe I have the same issue here.

I recently upgraded my Pro 6 from I believe 6.2.4, which was rock-solid, months of uptime with no issues.

After upgrading to 6.5.0 I've had what seem like two hard freezes in the last two weeks. The NAS seems to drop off the network. It won't respond to ping, I can't ssh to it, none of the shares are accessible, I can't reach the web interface, nothing.

The power button on the front panel is unresponsive, pressing it doesn't bring up the LCD screen. It seems to be locked up. I had to hold the power button to shut it down, then reboot it. Both times this brought it back up and it starts working again.

I began digging into the logs to see if there was anything I could find that looked immediately wrong, and I couldn't see anything right out of the gate, but I started going back through the syslog to see if I could determine at least what time the system actually froze.

I found this entry in kernel.log, checksum failure for the NIC that's connected to the network:

Jul 02 06:20:49 blackbox kernel: [295890.975286] eth0: hw csum failure
Jul 02 06:20:49 blackbox kernel: [295890.975299] CPU: 0 PID: 0 Comm: swapper/0 Tainted: P           O    4.1.21.x86_64.1 #1
Jul 02 06:20:49 blackbox kernel: [295890.975303] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS 080014  10/03/2008
Jul 02 06:20:49 blackbox kernel: [295890.975305]  0000000000000000 ffff88014fc03b08 ffffffff889b0fe5 ffff8800ab8f4000
Jul 02 06:20:49 blackbox kernel: [295890.975310]  ffff88009dbc6501 ffff88014fc03b28 ffffffff888af96d ffffffff8889c4b0
Jul 02 06:20:49 blackbox kernel: [295890.975314]  ffff88013741c200 ffff88014fc03b68 ffffffff888a3e47 ffff88014fc03b48
Jul 02 06:20:49 blackbox kernel: [295890.975318] Call Trace:
Jul 02 06:20:49 blackbox kernel: [295890.975320]  <IRQ>  [<ffffffff889b0fe5>] dump_stack+0x4d/0x63
Jul 02 06:20:49 blackbox kernel: [295890.975334]  [<ffffffff888af96d>] netdev_rx_csum_fault+0x3d/0x40
Jul 02 06:20:49 blackbox kernel: [295890.975338]  [<ffffffff8889c4b0>] ? csum_block_add_ext+0x30/0x30
Jul 02 06:20:49 blackbox kernel: [295890.975342]  [<ffffffff888a3e47>] __skb_checksum_complete+0xc7/0xd0
Jul 02 06:20:49 blackbox kernel: [295890.975347]  [<ffffffff88913f78>] icmp_rcv+0x1f8/0x3b0
Jul 02 06:20:49 blackbox kernel: [295890.975351]  [<ffffffff888df7c4>] ip_local_deliver_finish+0xa4/0x220
Jul 02 06:20:49 blackbox kernel: [295890.975354]  [<ffffffff888dfab6>] ip_local_deliver+0x36/0xb0
Jul 02 06:20:49 blackbox kernel: [295890.975357]  [<ffffffff888df720>] ? ip_rcv_finish+0x310/0x310
Jul 02 06:20:49 blackbox kernel: [295890.975360]  [<ffffffff888df521>] ip_rcv_finish+0x111/0x310
Jul 02 06:20:49 blackbox kernel: [295890.975363]  [<ffffffff888dfd7e>] ip_rcv+0x24e/0x3c0
Jul 02 06:20:49 blackbox kernel: [295890.975367]  [<ffffffff888aa85c>] __netif_receive_skb_core+0x53c/0x750
Jul 02 06:20:49 blackbox kernel: [295890.975370]  [<ffffffff888adb8c>] __netif_receive_skb+0x1c/0x70
Jul 02 06:20:49 blackbox kernel: [295890.975373]  [<ffffffff888add2e>] netif_receive_skb_internal+0x1e/0x90
Jul 02 06:20:49 blackbox kernel: [295890.975377]  [<ffffffff888addac>] netif_receive_skb_sk+0xc/0x10
Jul 02 06:20:49 blackbox kernel: [295890.975382]  [<ffffffff88747e43>] SkY2Poll+0xeb3/0x14b0
Jul 02 06:20:49 blackbox kernel: [295890.975386]  [<ffffffff88087b4d>] ? get_nohz_timer_target+0x3d/0x100
Jul 02 06:20:49 blackbox kernel: [295890.975389]  [<ffffffff88088001>] ? task_curr+0x1/0x30
Jul 02 06:20:49 blackbox kernel: [295890.975393]  [<ffffffff888ae0ec>] net_rx_action+0x12c/0x2c0
Jul 02 06:20:49 blackbox kernel: [295890.975397]  [<ffffffff8806b66a>] __do_softirq+0xda/0x1f0
Jul 02 06:20:49 blackbox kernel: [295890.975401]  [<ffffffff8806b966>] irq_exit+0x76/0xa0
Jul 02 06:20:49 blackbox kernel: [295890.975404]  [<ffffffff880052d0>] do_IRQ+0x60/0x100
Jul 02 06:20:49 blackbox kernel: [295890.975408]  [<ffffffff889b972b>] common_interrupt+0x6b/0x6b
Jul 02 06:20:49 blackbox kernel: [295890.975410]  <EOI>  [<ffffffff8800cbfb>] ? mwait_idle+0x5b/0x90
Jul 02 06:20:49 blackbox kernel: [295890.975417]  [<ffffffff8800d4aa>] arch_cpu_idle+0xa/0x10
Jul 02 06:20:49 blackbox kernel: [295890.975420]  [<ffffffff8809c6da>] cpu_startup_entry+0x18a/0x2a0
Jul 02 06:20:49 blackbox kernel: [295890.975424]  [<ffffffff889ab032>] rest_init+0x72/0x80
Jul 02 06:20:49 blackbox kernel: [295890.975428]  [<ffffffff88e38003>] start_kernel+0x4b1/0x4be
Jul 02 06:20:49 blackbox kernel: [295890.975431]  [<ffffffff88e3793f>] ? set_init_arg+0x58/0x58
Jul 02 06:20:49 blackbox kernel: [295890.975435]  [<ffffffff88e37568>] x86_64_start_reservations+0x2a/0x2c
Jul 02 06:20:49 blackbox kernel: [295890.975438]  [<ffffffff88e37627>] x86_64_start_kernel+0xbd/0xc1

The next log entry occurs at 12:28, when I restarted the box.

Strangely though, there's entries in the system log between 6:20 and the restart. Specifically, I have a cron script that runs every hour on the NAS and makes a GET request to a webserver I run, on the public internet. Syslog was showing that my cron script was running every hour on the hour as it should.

I then logged into my web server and checked the logs for the webapp my NAS communicates with. The webserver was seeing the GET requests coming in from the NAS. It's definitely the NAS, it's the only device that would hit this particular URL on the server, and it also passes a unique token as a paramater, so it's definitely the NAS checking in.

If this happens again and the NAS becomes unreachable like this, I'll wait another hour and see if it is still making GET requests out to the webserver while otherwise unresponsive. 

Wondering if 6.5.1 might have a fix for this, but I've read that people with Pro 6's are having fan issues with 6.5.1 so I deliberately didn't upgrade to that version.