1) I am using miningpoolhub coin switching and sometimes when DAG is recreated by coin switch or devfee mining it ends up with all cards having zero hashrate.
Can I prevent this somehow?
I have RX 570 ASUS Strix 4GB in my rigs and MoBos are ASUS Z270-A PRIME.
1. Just a speculation: the DAG of the previously mined coin is not unloaded from VRAM and when generating new DAG for newly-switched coin, the GPU runs out of memory, i.e. you mine ETH, the DAG is ~2.18GB, later the pool switches your task to ETC, with a ~2.25GB DAG. 2.18+2.25>4 GB, out of memory error, OpenCL crashes, 0 hashrate on all GPUs. That might be a Linux-sensitive issue, haven't met it on Windows.
Since you are mining on MPH, you are switching between 4 coins: ETH, ETC, EXP and Musicoin. Is all the hassle worthy the extra 5-10% you get over mining a single chain? Factor in all the time your rigs are not effectively mining.
BTW, I would mine only ETH or ETC. Screw Expanse and Musicoin, first is scammy, later is laggard.