"Check Image" Utility causing a Network/Internet black out when being run after a back up.

Hi,

I am having an issue with my Aomei Backupper and wondering if anyone can help at all. 

I am currently use the program back up three laptops to WDMYCLOUD NAS connected via a BT HOME HUB5 router via Ethernet. The backup gets backed up without an issue. However, from one of my laptops when I run the “check image” utility or when I select this is in the options menu for back up my network crashes on that computer, I can’t access the internet or any network share, if I cancel it then everything returns to normal instantly, if I let it run then I can’t access the internet or network shares using that laptop. This problem also occurs to the other laptops but it doesnt completely block out the network, on the other laptops, on one of them it slows its right down where even google takes ages. So this gives me a indication check image when being run is stopping the network, could this be because of the large file size and the router cant cope with it? although it backed it up the same way without issues. 

IF I continue to leave the Check Image running it gets to about 40% and then states read fail. 

I initially suspected the router was over heating but it’s not and I am able to access the internet and shares using the other laptops when check image is being run on the laptop thats runnning the check image utility. I really like this software and I downloaded it to try before I purchase the pro version it but for some reason I am getting the above issue. I did purchase Acronis but got refund after I got into an issue with the software telling me the backeds up copy of the data was corrupted due to being sat on my NAS. This is apprantly the way WD manage their share accounts and the software couldnt work out I had privialiges to the share.

I have rebooted the NAS and computer with the same issue. the backup is 244gb and backed up incrementally stored on the NAS. What could be causing this? could it be because the file is too large for the router?