Please use the following command to add the testnet enode manually:

admin.addPeer("enode://eb6b4724b8ef510846ddc69de30e844eb710eeb312384512d3d2dfd0f9f9cb38e0591d64c08b4ea2966c220464bcf9897393718339a97e01a75851a026e31d56@34.235.151.111:22334")