Problem with re(4) Ethernet driver has resurfaced in 11-STABLE and HEAD

I recently updated my 10.1-STABLE to 11.0-STABLE and find I can no longer connect with the Ethernet.

dhclient re0 produces

DHCPDISCOVER on re0 to 255.255.255.255 port 67 interval 4
DHCPDISCOVER on re0 to 255.255.255.255 port 67 interval 11
DHCPDISCOVER on re0 to 255.255.255.255 port 67 interval 19
DHCPDISCOVER on re0 to 255.255.255.255 port 67 interval 7
DHCPDISCOVER on re0 to 255.255.255.255 port 67 interval 14
DHCPDISCOVER on re0 to 255.255.255.255 port 67 interval 5
No DHCPOFFERS received.
No working leases in persistent database - sleeping.

uname -a shows

FreeBSD amelia2 11.0-STABLE FreeBSD 11.0-STABLE #1 r317932: Mon May  8 23:23:37 UTC 2017     root_at_amelia2:/usr/obj/usr/src11/sys/SANDY11NC  amd64

Relevant lines from /var/run/dmesg.boot are

re0: <RealTek 8168/8111 B/C/CP/D/DP/E/F/G PCIe Gigabit Ethernet> port 0xe000-0xe0ff mem 0xf7d04000-0xf7d04fff,0xf7d00000-0xf7d03fff irq 17 at device 0.0 on pci2
re0: Using 1 MSI-X message
re0: Chip rev. 0x2c800000
re0: MAC rev. 0x00100000
miibus0: <MII bus> on re0
rgephy0: <RTL8169S/8110S/8211 1000BASE-T media interface> PHY 1 on miibus0
rgephy0:  none, 10baseT, 10baseT-FDX, 10baseT-FDX-flow, 100baseTX, 100baseTX-FDX, 100baseTX-FDX-flow, 1000baseT, 1000baseT-master, 1000baseT-FDX, 1000baseT-FDX-master, 1000baseT-FDX-flow, 1000baseT-FDX-flow-master, auto, auto-flow
re0: Using defaults for TSO: 65518/35/2048
re0: Ethernet address: d4:3d:7e:97:17:e2
re0: netmap queues/slots: TX 1/256, RX 1/256

Problem shows much quicker in my recent build of HEAD (12-current), where 
dhclient re0
gives just a couple lines screen output before crashing into debugger 
db> prompt

Build host for 12-current installation was the recent build of 11.0-STABLE amd64.

Kernel strings there show

__page_fault.read
__page_fault.write
amd64
_at_(#)FreeBSD 12.0-CURRENT #1 r318262: Sun May 14 09:37:30 UTC 2017
FreeBSD 12.0-CURRENT #1 r318262: Sun May 14 09:37:30 UTC 2017
    root_at_amelia4:/BETA1/usr/obj/BETA1/usr/src/sys/SANDY12NC
FreeBSD clang version 4.0.0 (tags/RELEASE_400/final 297347) (based on LLVM 4.0.0)
FreeBSD
12.0-CURRENT
SANDY11NC

It looks like I can connect to Internet with Hiro H50191 USB wireless adapter, driver rsu, but I am not sure of its stability on 11.0-STABLE and 12.0-current..

Tom