If you have a problem loggin in, try to edit your host file like that:
127.0.0.1 localhost
62.38.148.29 l2authd.lineage2.com
62.38.148.29 l2testauthd.lineage2.com
216.107.250.194 nprotect.lineage2.com
or
78.47.101.197 nProtect.lineage2.com
One of the two last lines should work (not both!)
or DOWNLOAD it ready made host here. (rename it as "host" first and then put it in the right place: C:\windows\system 32\drivers\etc)
or look next topic (GG killer)