@sing.li I could not add on our exchange so i’m creating a new topic.
Answering to that message
Ok, noted, i think i read that somewhere indeed.
But the thing is i’m not above 2GB.
Once i extract the tarball of my backup and run du -hs in the folder it says it is 597MB (533MB compressed in tar).
Should i try to delete files to make it even smaller?
When i import i only get this error in mongorestore.log though 
ERROR: ld.so: object '/usr/lib/arm-linux-gnueabihf/libarmmem.so' from /etc/ld.so.preload cannot be preloaded (cannot open shared object file): ignored.
connected to: 127.0.0.1
2019-01-12T18:02:26.765+0100 var/snap/rocketchat-server/1278/dump/parties/rocketchat_livechat_visitor.bson
2019-01-12T18:02:26.765+0100 going into namespace [parties.rocketchat_livechat_visitor]
2019-01-12T18:02:26.765+0100 dropping
assertion: 15936 Creating collection parties.rocketchat_livechat_visitor failed. Errmsg: exception: can't map file memory - mongo requires 64 bit build for larger datasets