You can remove all those lines from conf file and you just add nodes there.
Also , check does modem block port 6666
Miner start with this

It seems the problem in rpcport=6666.
Why do you set it?
There was another user with similar problem.
I need to know why such users have set up rpcport=6666

Because they can.

I often spin up another instance of a coin, copying the datdadir and running the second client on a different port alongside the first.

Cheers

Graham

But why do they all use exactly 6666 port for rpc service. Why do they try to use exactly the same port as embedded mining pool port?
Coincidence?

It is very little probability to set exactly rpcport=6666, not 6665, not 6667, not 12345, not any other number. Why 6666?
Is there any reason why people set it exactly 6666? It is very interesting.

Why, mister Anderson?

Is there any instruction for other coin to set rpcport=6666, the instruction you have followed?

May be we need to change default pool port to another?

 Is there any coinmarketcap indicator live at the moment or will this be active in a later stage of the project? 

download bootstrap from here
https://github.com/datacoinproject/datacoin/releases
it will speed up syncing

It seems the problem in Transaction total size: 115980 bytes.
The old wallets can't receive such big transactions into memory pool (but can receive it in blockchain).

It is a big problem of old wallets because of it prevents to accept transactions with 100kb data.

I have resolved it in 0.15.99.8 wallet, but problem will remain until most of network migrate to new wallet.

To avoid such problems with current network make transactions about 70 kb. (it is about 3-4 dtc of fee per once)

Try the followings.
1. Right click on the transaction in the list of transactions, then abandon it. Restart app.

If it doesn't help .
2. Backup wallet.dat. Start dtc with rescan wallet flags. f.e: "datacoin-qt -rescan -zapwallettxes=1"

P.S. And don't worry. Your coins is still yours.