Hey, I don't know if this is helpful, but here are some lines from “dmesg | grep sky”:

[    0.352160] tun: (C) 1999-2004 Max Krasnyansky <email address hidden>
[    1.046363] sky2 driver version 1.25
[    1.046421] sky2 0000:08:00.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16
[    1.046441] sky2 0000:08:00.0: setting latency timer to 64
[    1.046473] sky2 0000:08:00.0: Yukon-2 FE chip revision 1
[    1.046606] sky2 0000:08:00.0: irq 29 for MSI/MSI-X
[    1.051300] sky2 eth0: addr 00:1a:80:9f:92:db
[   33.167856] sky2 eth0: enabling interface
[   34.945786] sky2 eth0: Link is up at 100 Mbps, full duplex, flow control both
[44089.540092] sky2 eth0: disabling interface
[44096.712033] sky2 0000:08:00.0: Refused to change power state, currently in D3
[44096.712051] sky2 0000:08:00.0: restoring config space at offset 0xf (was 0xffffffff, writing 0x105)
[44096.712060] sky2 0000:08:00.0: restoring config space at offset 0xe (was 0xffffffff, writing 0x0)
[44096.712068] sky2 0000:08:00.0: restoring config space at offset 0xd (was 0xffffffff, writing 0x48)
[44096.712076] sky2 0000:08:00.0: restoring config space at offset 0xc (was 0xffffffff, writing 0x0)
[44096.712083] sky2 0000:08:00.0: restoring config space at offset 0xb (was 0xffffffff, writing 0x9005104d)
[44096.712093] sky2 0000:08:00.0: restoring config space at offset 0xa (was 0xffffffff, writing 0x0)
[44096.712101] sky2 0000:08:00.0: restoring config space at offset 0x9 (was 0xffffffff, writing 0x0)
[44096.712111] sky2 0000:08:00.0: restoring config space at offset 0x8 (was 0xffffffff, writing 0x0)
[44096.712121] sky2 0000:08:00.0: restoring config space at offset 0x7 (was 0xffffffff, writing 0x0)
[44096.712130] sky2 0000:08:00.0: restoring config space at offset 0x6 (was 0xffffffff, writing 0x6001)
[44096.712140] sky2 0000:08:00.0: restoring config space at offset 0x5 (was 0xffffffff, writing 0x0)
[44096.712150] sky2 0000:08:00.0: restoring config space at offset 0x4 (was 0xffffffff, writing 0xfc000004)
[44096.712158] sky2 0000:08:00.0: restoring config space at offset 0x3 (was 0xffffffff, writing 0x10)
[44096.712168] sky2 0000:08:00.0: restoring config space at offset 0x2 (was 0xffffffff, writing 0x2000016)
[44096.712175] sky2 0000:08:00.0: restoring config space at offset 0x1 (was 0xffffffff, writing 0x100507)
[44096.712185] sky2 0000:08:00.0: restoring config space at offset 0x0 (was 0xffffffff, writing 0x435111ab)
[44097.308074] sky2 0000:08:00.0: Refused to change power state, currently in D3
[44102.966013] sky2 0000:08:00.0: eth0: phy I/O error
[44102.966025] sky2 0000:08:00.0: eth0: phy I/O error
[44102.966032] sky2 0000:08:00.0: eth0: phy I/O error
[44102.966039] sky2 0000:08:00.0: eth0: phy I/O error
[44102.966046] sky2 0000:08:00.0: eth0: phy I/O error
[44102.966053] sky2 0000:08:00.0: eth0: phy I/O error
[44102.966060] sky2 0000:08:00.0: eth0: phy I/O error
[44102.966067] sky2 0000:08:00.0: eth0: phy I/O error
[44102.966073] sky2 0000:08:00.0: eth0: phy I/O error
[44102.966080] sky2 0000:08:00.0: eth0: phy I/O error
[44102.966086] sky2 0000:08:00.0: eth0: phy I/O error
[44102.966093] sky2 0000:08:00.0: eth0: phy I/O error
[44102.966411] sky2 eth0: enabling interface

The second time period, after 44000, is post-resume.
The ethernet adapter won't come back up.

What's the way forward, hope for the next kernel update to undo what was done before?