Thanks for all good advice.
I installed the gateway from scratch with a newly formatted SD card but still the same RPi following the instructions on the LAB’s pages.
I am using the same EUI read from MAC address of the RPi and restored (I guess) the gateway on V2.
To my surprise It is working again and the gateway is visible in my console with the “green” light, also my things-nodes are visible again in MyDevices / Cayenne
The frustration I was not able to hide was more or less PANIC driven !!! Not cool !
So to summarise : The SD card is the weakest link (next is my nerve)
Glad to hear you are back online 
… & with TTN 
Often the case and regularly discussed on the Forum - use search to look for peoples suggestions wrt mitigation techniques (increase SD size/oversize, Log2Ram, etc). FWIW I have a fleet of of which >20GW’s supported by SD Cards + numerous test set ups from over last ~2.5-3years and have just 2 failures in the field, with 2 or 3 others in lab, all were caused by intermittent power/unscheduled/unclean shutdowns etc. with 1 shear stupidity on my part!!)
removed, getting off-topic
Dear descartes,
I’m trying to migrate my LPS8-gw to V3 but have two automatically generated entries (the V2-status is now “unkown”):
You warned not to delete a Gateway EUI.
I already switched to the v3-server address in the LPS8-configuration. What is the best way to continue?
Best regards, Thomas
What does the log on the LPS8 say - it is getting ACK’s back from the gateway server?
You may want to search the forum for LPS8 as there have been a number of different posts on that model of late.
hi i need some information please.
i registered my gateway , After a while I deleted it now I want to register it again but it tells me that it exists, I have to wait or what do I have to do?
Posting the exact error message will make it easier to help you.
What is ‘it’? If its the Gateway-ID just choose another one… (GW ID is immutable in the console and once used and GW deleted it cant be taken again… Gateway EUI can be used over and is to be considered immutable on the GW itself, unless it is a GW that allows for recoding of the GW EUI…)
Thanks I think the immutable id, the problem is that suddenly I’m configuring the wifi wrong because it appears disconnected, so my question now is if when I deactivate the network point generated by the dragino, do I have to have it connected by lan to the router?
Personally, given the choice, I always set up on wired ENet 1st and only then look to move over to WiFi, with the GW then acting as just another (DHCP?) client to host Network AP. Hoping in and out of AP mode I find increases chance of something going wrong…. But then I’m ‘all fingers and thumbs’ 
ohh ty How can I recover the gateway that I deleted or make it my own?
If deleted then try reregistering using the GW EUI and create a new Gateway ID (note system may auto generate an ID based on the EUI which of course will be a repeat of the one previously used - just ignore and over write with a name more convenient for you e.g. gatriasas-gw-001 )
What is the EUI?