Network issues in VBox 5.1.8

[iwicfm666]

I'm running 64bit VBox 5.1.8 with a Win7 guest on a Mageia 5 host.

After upgrading to 5.1.8, the virtual network will not time out in the Win7 guest. In other words, any app that tries to access any unavailable network resource freezes indefinitely. The only solution is to uncheck/deactivate the network device via Devices > Network > Adapter 1, which immediately allows the app to wake up and complain about the network being unavailable.

Downgrading to 5.0.16 fixes this network problem.

I also tested this on the latest build (5.1.9 r111957) which has the same problem.

Specific examples: an emulator for a mainframe, Notepad++ with a file open that lives on the network at work, xplorer2 with a network folder open. All of these are completely frozen while the network is unavailable.

$ ifconfig -a
eno1: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether 5c:f9:dd:5c:25:98  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 17  

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 0  (Local Loopback)
        RX packets 703  bytes 67338 (65.7 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 703  bytes 67338 (65.7 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

vboxnet0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.56.1  netmask 255.255.255.0  broadcast 192.168.56.255
        inet6 fe80::800:27ff:fe00:0  prefixlen 64  scopeid 0x20<link>
        ether 0a:00:27:00:00:00  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 14  bytes 1187 (1.1 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wlp12s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.64  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::221:6aff:fec5:749a  prefixlen 64  scopeid 0x20<link>
        inet6 2602:30a:2c54:2e20:221:6aff:fec5:749a  prefixlen 64  scopeid 0x0<global>
        ether 00:21:6a:c5:74:9a  txqueuelen 1000  (Ethernet)
        RX packets 15944  bytes 10006776 (9.5 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 14417  bytes 3582297 (3.4 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

$ netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
0.0.0.0         192.168.1.254   0.0.0.0         UG        0 0          0 wlp12s0
192.168.1.0     0.0.0.0         255.255.255.0   U         0 0          0 wlp12s0
192.168.56.0    0.0.0.0         255.255.255.0   U         0 0          0 vboxnet0