Add this plugin to hopefully prevent people from crashing playerservers because they keep sending too many packets, not sure if its compatible with versions below 1.12 but its compatible with 1.12, 1.13, 1.14, and 1.15 (as it said they tested it), you could send over 40k packets and yet the playerserver doesn't crash with this plugin, so here is the link: https://www.spigotmc.org/resources/packet-limiter.70217/