This is the only possible answer to your question.
Without knowing anything about your setup, nobody can help you.
There's obviously no switch "make everything work perfectly" which is disabled by default.and has just to be turned on.
So please share some information with us, the minimum would be this:
What's your uplink? You said it's coming from a Groove - is that your device or your provider's CPE? Which IP are you getting from there?
Where are those devices located, how far is it to the clients? What's the clients' hardware?
What is going on in your network while affected devices have problems?
Post a config of your router.
If the groove is in your possesion, post a config of it too.
Then you have a chance to get help.
MTCNA, MTCUME, MTCWE
There are 10 types of people: Those who understand binary and those who don't.
There are two types of people: Those who can extrapolate from incomplete data