06:29:15:493   1458   WATCHDOG: GPU 0 hangs in OpenCL call, exit

setx GPU_FORCE_64BIT_PTR 0
setx GPU_MAX_HEAP_SIZE 100
setx GPU_USE_SYNC_OBJECTS 1
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_SINGLE_ALLOC_PERCENT 100
EthDcrMiner64.exe -epool eth-eu1.nanopool.org:9999 -ewal xxxxx -epsw x -mode 1 -ftime 10 -cclock 1200 -mclock 2100,2150,2150,2150,2250,2150 -cvddc 875 -mvddc 875 -gser 0 -tt 65 -tstop 80 -asm 2 -etha 0 -mport 0

Getting the same - I guess their Stratum is not using SSL so you're getting this '(unsecure)'.
Have you tried only removing the "-allpools 1" or did you remove completely?

Try to remove this part first
"-ftime 10 -cclock 1200 -mclock 2200,2200,2100,2200,2200,2100 -cvddc 900 -mvddc 900 -gser 0 -tt 65 -tstop 80 -asm 2 -etha 0 -mport 0 -allpools 1"

Then try again.
And maybe your server pool you are connecting "-allpool" is not supported.

Download the latest claymore here https://bitcointalk.org/index.php?topic=1433925.0

20:34:25:673   18c0   ETH: Stratum - connecting to 'eth-eu1.nanopool.org' <164.132.108.171> port 9999 (unsecure)

20:34:25:673   18c0   ETH: Stratum - connecting to 'eth-eu1.nanopool.org' <164.132.108.171> port 9999 (unsecure)

setx GPU_FORCE_64BIT_PTR 0
setx GPU_MAX_HEAP_SIZE 100
setx GPU_USE_SYNC_OBJECTS 1
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_SINGLE_ALLOC_PERCENT 100

EthDcrMiner64.exe -epool eth-eu1.nanopool.org:9999 -ewal 0xMYWALLETADRESS.Worker1/MYEMAIL@gmail.com -epsw x -mode 1 -ftime 10 -cclock 1200 -mclock 2200,2200,2100,2200,2200,2100 -cvddc 900 -mvddc 900 -gser 0 -tt 65 -tstop 80 -asm 2 -etha 0 -mport 0 -allpools 1

This pool (eth-eu1.nanopool.org) does not support Ethereum addresses as login (or requires worker name in "Login.Worker" format) and cannot be used for devfee mining, therefore it is not supported.

A variation of hash rate of 10-30 MH/S is acceptable and always happens when you are mining. Make sure that you are not performing other tasks with this mining rig, otherwise this fluctuation in the hash rate is normal.

Only GPU 3 and 4 that always fluctuated? (as shown in your pics) If it yes, you can focus on those two.

Drop until 8 MH/s on each (GPU 3 and 4) isn't normal, you can start with check memory error (since you are using AMD card you can use HWinfo)

I used claymore v11.0 and never had any issue on reconnecting when the internet rebooting or stop like the above said the claymore will restart in 20 seconds to reconnect.
This version works for me when mining ethereum but when overclocking it too high it crashes so just setup it with enough clock.

Where are you seeing the flucuation? At the pool or within Claymore?

-ewal -epsw x -mode 1 -ftime 10 -dcri 12 -asm 2 -etha 0 -cclock 1200 -mclock 2100 -cvddc 900 -mvddc 900 -allpools 1 -gser 0 -minspeed 120 -tt 58 -tstop 80 -platform 1 -mport 0

You can use Add2PSU adapter for starting more than 1 PSU when you boot up your mining rig. Really great little adapter that can help you to multiply your much-needed PCIE connectors.

Hi,
I am using both mvddc and cvddc in Claymore miner.
You should try -mvddc 900 -cvddc 900.
Let it run for a while, and if it's stable, then you can try lowering voltage, e.g. 875, until you find best settings.
You can also underclock each gpu seperate, e.g. -mvddc 900,880,910... -cvddc 875,890,910...
It doesn't mean that all gpu's are gonna run on same settings, even though it's the same brand and model.
I found this tutorial, it maybe helps you https://steemit.com/ethereummining/@nesahayward/eth-ethereum-mining-with-rx-580-8g-8gb-claymore-settings

You can also try OverdriveNtool for overclocking and undervolting.
Try this tutorial https://mining.help/2017/12/10/windows-10-mining-guide-for-amd-gpus-12-gpu-supported/