Error code 2003 / can't login on android Lenovo Tablet

 I would be really grateful if you could give me some advice on why I keep getting Error code 5003 on my lenovo tab m10 plus (3rd gen) android tablet. The first few times I used zoom on it, there was no problem (I also have it installed on my Motorola G8 plus and it works fine there). I have tried reinstalling, clearing the cache etc on both items and individually but it still won't let me sign in on the tablet. If I try to sign in with Google identity, I get the error code 2003. If I sign in with my zoom account password (which works on smartphone and on laptop), I get the simple message "login failed. Failed to connect to Zoom". Really frustrating as I got this tablet particularly to use zoom. Many thanks for any help, Rick