Bad lag for second player

My friend has bad lag on PC. I'm not certain if it's me,  or them, but the connection meter is constantly orange and it has made timing based challenges a giant pain for them. For me,  as the host I'd assume, it's perfectly fine. Any suggestions on how to improve  the connection quality? If I run a speed test to a server in their area, it reads as 119 ms, 65 down, 5 up. I know  it'll never be perfect, but it seemed like the actual lag was closer to 3-400 MS.