Network port udp:30303 could not be mapped: no UPnP or NAT-PMP router discovered

[lanmp]

2018-06-01 15:48:31 Starting server...
E0601 15:48:32.422292 p2p/nat/nat.go:114] Network port udp:30303 could not be mapped: no UPnP or NAT-PMP router discovered
2018-06-01 15:48:32 UDP listening. Client enode: enode://f59ec567b75ab8f0c1b3cdd088dab604c691294413c1709d46e541d91570a68e484adfee1edea75e33588d18db759d870290854703f6bc3f052aa328c0161db5@[::]:30303
E0601 15:48:32.442854 p2p/nat/nat.go:114] Network port tcp:30303 could not be mapped: no UPnP or NAT-PMP router discovered
2018-06-01 15:48:32 IPC endpoint opened: /root/.ethereum-classic/mainnet/geth.ipc
Welcome to the Geth JavaScript console!

instance: Geth/source/linux/go1.10.2

The version >4.1.1
Cannot sync block

[whilei]

Hey @lanmp -- the reason you can't sync is because you're on geth 4.1.1, which is incompatible with the planned hardfork at block 5900000 that happened this past week. You'll need to upgrade to at least Geth 5+.

As for the UPnP "error" -- not to worry, this is actually a harmless log. I've got PR #611 in already to relegate the severity as to not be so alarming.