Problems with latency and jitter

[EDODRISCOLL]

OK ... we're a band and currently trying to rehearse together remotely as we're all on COVID lockdown. I'm the vocalist and the last couple of days I've been trying to rehearse with guitarist. We're both using ADSL and both have fibre. We keep getting latency spikes and jitter ... ther's no consistency ... everything will be OK for 60 seconds and then they'll be a jump ... like a needle hopping on vinyl. I'm showing all green at home as is guitarist ... any ideas on what might be going on and how we can improve things please? Worried it's going to get even tougher when bass and drummer join in ...