1. The Status for my remote masternodes in "My Masternode" tab sometimes automatically change from "ENABLED" to "MISSING", while having NO Internet connection problems. Do you maybe know the reason why its sometimes automatically change from "ENABLED" to "MISSING"?
2. As you've mentioned that "the remote masternode on vps will not stop", does this means that an automatically Status change from "ENABLED" to "MISSING" on my local wallet won't affect my remote masternodes then as well?
98% of the time, if a MN is MISSING that means that it has stopped working for some reason, but this is usually not a local problem. When it says MISSING in your local wallet, that means that the wallet has scanned for the MN and has been unable to confirm that it's working. Sometimes it's a false alarm, but most of the time if it's MISSING, it's really not working. Regardless, if you start a MN locally, it will often show up as ENABLED for an hour or two even if something really is broken. So you should always wait a few hours to make sure it stays enabled before shutting down your local wallet.
There are many reasons why a MN may show up as MISSING: If you have screwed something up in your local masternode.conf or the remote pivx.conf, you will usually receive an error message of some kind and it won't say ENABLED in the first place. If it is saying ENABLED but then changing to MISSING after a while, then it's more likely that the remote VPS stopped working (i.e., a server problem), or the remote wallet stopped syncing (i.e., a software problem). Make sure the remote wallet is fully synced (this is in putty or whatever you're using):
./pivx-cli getinfo
Once it's synced, make sure to start the remote node:
./pivx-cli masternode start
...chances are you'll get the 'not capable, waiting for remote activation' message. That means you need to go into your local wallet and start the MN there.
Don't use 'start many'--use start-alias YOURMASTERNODENAME instead (even if you're starting multiple; start many is sensitive for some reason).
For reference here's what my conf files look like; feel free to copy--no guarantees they'll help you, but it's worth a shot.
Remote pivx.conf:
rpcuser=XXX
rpcpassword=XXX
rpcallowip=127.0.0.1
listen=1
server=1
daemon=1
logtimestamps=1
bantime=50
maxconnections=256
masternode=1
masternodeprivkey=XXX
addnode=108.61.151.69
addnode=173.245.158.8
addnode=coin-server.com
addnode=s3v3nh4cks.ddns.net
Local masternode.conf (%appdata% --> PIVX in Windows):
MNNAME IP.IP.IP.IP:51472 MNPRIVKEY 10KPIVXTXID 1 or 0
^ need a line like this for each MN you have. Of course, double check that all your private keys and TX IDs are correct, etc.
A MN will have to stay enabled for at least a couple of days to receive its first payout.
If it's still not working, you can get more opinions on Slack:
slack.pivx.org