LATENCY, mostly TOTAL LATENCY

[StuartR]

Thanks, Stuart... your advice should go over really well in the household since I'm doing 3-4 JK sessions a week, mostly in the evenings --- "Guess what, honey? Not only am I going to be in the studio in another JamKazam session, you can't watch tv or use your computer while I'm out there! How about knitting? You could knit me something [runs away]".

Any suggestions on a router that won't get me living in the garage? Thanks again...

>>>
Another router/modem is hardly gonna do any good when your household is netflixing, gaming a/o up-/downloading at the same time you're trying to do anything with online audio. There will always be 'noise' = jitter = latency.
A 'sneaky' local QoS shaping (and bandwidth pools), giving your UDP traffic priority could help some, but don't expect miracles.
'Having the road to yourself' and disabling/stopping all other network (LAN & inet) use is really the best(only?) key to success where congestion/noise/jitter is in play.

I hear you with the "household" though. A band friend of mine can't even get 2,5h a week for himself to play online - had to stop that collab.

I beg to differ. A properly designed router will help greatly. There are several choices that I personally have experience with. The best, IMHO, is IQrouter, designed specifically to help in this regard. It's very affordable and easy to setup to allow the highest priority to your outgoing realtime audio packets. A second option is to use the openWRT router software on your existing router (if it's supported). You can check their site for a list. Thirdly, routers from ASUS have very robust QoS abilities and you can easily assign bandwidth and protocol priorities to specific devices. Also, any Windows PC Jamkazam users can readily create a QoS policy on their machine to mark all outgoing Jamkazam UDP packets as high priority (think VOIP). This will place them ahead of normal incoming traffic in your QoS-enabled router.
So there's a lot you can easily and affordably do.

In your particular case, I'd consider giving them back their rented modem/router and purchasing your own DOCSIS 3.x modem and an IQrouter. Total cost around $200 and will pay for itself in a year or so depending on the rental amount you're currently paying.