can't contact back to the Cuckoo Host.

[Natruel]

When i run the cuckoo,there occurs a error.Here it is:
Error processing task #5: it appears that the Virtual Machine hasn't been able to contact back to the Cuckoo Host. There could be a few reasons for this, please refer to our documentation on the matter: https://cuckoo.sh/docs/faq/index.html#troubleshooting-vm-network-configuration

After i looked up the https://cuckoo.sh/docs/faq/index.html#troubleshooting-vm-network-configuration,i still can't solve it.So i think i need some help.By the way, the host can ping the vm successfully and the vm can ping the host successfully too.

[Natruel]

i think i have solved the problem, but it's not satisfying.Becasue, according to the .conf file:
cuckoo.conf:
[resultserver]：
The Result Server is used to receive in real time the behavioral logs
produced by the analyzer.
Specify the IP address of the host. The analysis machines should be able
to contact the host through such address, so make sure it's valid.
NOTE: if you set resultserver IP to 0.0.0.0 you have to set the option
resultserver_ip for all your virtual machines in machinery configuration.
ip = 192.168.56.1

Specify a port number to bind the result server on. Set to 0 to use a random
port.
port = 2042

virtualbox.conf:
(Optional) Specify the IP of the Result Server, as your virtual machine sees it.
The Result Server will always bind to the address and port specified in cuckoo.conf,
however you could set up your virtual network to use NAT/PAT, so you can specify here
the IP address for the Result Server as your machine sees it. If you don't specify an
address here, the machine will use the default value from cuckoo.conf.
NOTE: if you set this option you have to set result server IP to 0.0.0.0 in cuckoo.conf.
Example:
resultserver_ip =

(Optional) Specify the port for the Result Server, as your virtual machine sees it.
The Result Server will always bind to the address and port specified in cuckoo.conf,
however you could set up your virtual network to use NAT/PAT, so you can specify here
the port for the Result Server as your machine sees it. If you don't specify a port
here, the machine will use the default value from cuckoo.conf.
Example:
resultserver_port =

it seems that i have two options when i run the cuckoo.One is that i need to specify the ip and port in the cuckoo.conf, the other is that i need to specify the resultserver_ip and port in the virtualbox.conf. But when i chose the latter to run the cuckoo,it occurs the porblems that i mentioned above. And it seems that i must chose to specify the ip and port in cuckoo.conf so that the cuckoo can run successfully. But there also have another strange problem that when i shutdown my computer and start it again, it occurs an error:
(problem two:)
CuckooCriticalError: Unable to bind ResultServer on 192.168.56.1:2042 [Errno 99] Cannot assign requested address. This usually happens when you start Cuckoo without bringing up the virtual interface associated with the ResultServer IP address. Please refer to https://cuckoo.sh/docs/faq/#troubles-problem for more information.

it can be solved by choosing the second method i mentioned above, and after that , it will occurs the problem i mentioned firstly again. It's so disappointing! Finally,i found it need to restart the guest to slove the problem two which means that i need to restart my guest everytime when i want to run the cuckoo...