Use stratum also for decred.
Replace
-dpool http://dcr.suprnova.cc:9112 with
-dpool stratum+tcp://dcr.suprnova.cc:2252The rejects will drop to 1-3%

And You have to wait for almost 24h for DCR confirmation.
Thanks that made a difference btw can this Cannot parse JSON! be ignored?
ETH: Stratum - Connected
DCR: Stratum - Connected
Need to check DAG file (epoch #46), starting...
ETH: Authorized
Cannot parse JSON!
DCR: Authorized
DAG file (epoch #46) is ok.
Need to check next DAG file (epoch #47) in back
Applying DAG epoch #46 for GPU #0
Create GPU buffer for GPU #0
Applying DAG epoch #46 for GPU #0 done
Applying DAG epoch #46 for GPU #1
Create GPU buffer for GPU #1
Applying DAG epoch #46 for GPU #1 done
DAG file (epoch #47) is ok.
Ya, I see the same after switvhing to supernova stratum. It caused the miner to constantly restart (with watchdog), so I've deleted my DAG files and having the miner regenerate them. Not really sure if that will help or not...