Do I need to configure the dlink to a specific subnet... if so how?
Only if the factory default LAN subnet is the same as your ISP router's subnet. Do you have access to the User manual of that D-Link?
MOST home network routers allow you to change the IP range of the subnet. It wil probably be somewhere in te BASIC settings of "LAN" on the D-Link.
Factory settings for it is to pull an IP address from ISP and provide local (192.168.x.x) addresses to devices connected to it.
Now this D-Link is pulling an IP address from your ISP router and this is its WAN address.
Correct me if I'm wrong.. I changed the standard IP of 192.168.0.1 to 192.168.0.5; but if I want there to be a subnet...then I need to use e.g. 192.168.1.5 right?
Difficult to answer that question. Make sure there's no conflict between the ISP router and your D-Link, they have to be on 2 different subnets.
Post some screenshots if you are stuck.
I was able to setup the 2nd router.. changed all IP wan settings...and it started hashing... but after about 5min I lost the internet connection again.
It seems a bit more stable, but not stable enough. I switched off 2 ants and keep mining with 5... Expecting an 8th miner friday...so I hope everything is sorted by then.