An unstable or weak connection can be disruptive to your session, workshop or class, so it's best to do what you reasonably can to troubleshoot this - systematically - beforehand, as far as possible.
A small thing can make a great deal of difference - both to your experience of being online and how you feel about it - if you think of it in terms of a mindfulness and (self-)compassion practice it can entirely change the experience! It's really worth giving this whole area some patient, systematic thought well in advance.
In the first instance, it's generally best not to use a mobile phone, if you can avoid that - although that may, of course, be your only option. The controls on Zoom are generally somewhat more limited or less easy to use on mobiles. Depending on what the set-up is in your household, the mobile signal may be weaker (though this is not always the case). If you can use a laptop, or perhaps a tablet, you may find things work better and you have greater functionality.
Equally important is exploring the possibility of limiting the use of other online activity within your home (including game consoles, live streaming and automatic data back-up, including on your own device) at the same time as your session, workshop or class. These activities can significantly reduce available bandwidth, contribute to interference and reduce the stability of your internet connection - it can be well worth thinking ahead (and, if necessary, negotiating with other household members!).
Closing other applications - as well as other windows or tabs in your browser (such as Chrome or Safari) - can make a significant difference to the stability of your connection, and you are advised to do this before connecting over Zoom.
If you can, try connecting your laptop directly into your router/modem with an ethernet cable (and appropriate adapter if necessary, both readily available from online suppliers) - instead of wirelessly - and/or installing a booster unit or powerline adapter. Search online - if you can - for information and suppliers (plenty of both!). There is a lot of good information on the internet about how to improve your internet connectivity.
Additionally, your internet service provider (ISP) can be extremely helpful - I've found advisers very willing to talk things through patiently and creatively, so it can be well worth the wait to get through to an operator!
They should be able to talk you through some additional options and make helpful suggestions. they can check your connectivity and upload/download rates, confirm whether there are any reported network issues in your area and, if necessary, arrange for local network tests to be made. They can also offer guidance about checking the connections within your own home - including making sure that cables are not frayed, pinched or otherwise damaged, and possibly replacing the ADSL filter/splitter that plugs into the main (BT or another supplier) connection box (these filters costs very little, and are notorious for lasting only a matter of months - you should be able to order a replacement online).
Beyond these basic considerations - which you would be well advised to systematically explore - there are, however, some things over which you may have absolutely no control: such as living either in an area where a lot of people in other residences in the same building or neighbourhood are using broadband simultaneously (particularly at times of peak usage), or living in an area with poor broadband coverage. As - apart from moving home! - there's little you can do about either, it's a very good idea to do what you can to improve the things over which you might well have some influence ...
In any case, we are all constrained by the prevailing conditions, and can only do what we reasonably can to muddle our way through ... patiently and mindfully.