I think this can make a fantastic tank/ support from an unlikely source, barbarian. Start with 3 levels of barbarian to pick up the ancestral guardian subclass. From their take monk from there. This is great as now you can focus on dex and con for your ac making you tougher overall. A weakness of the ancestral barbarian is you can only hit 1 creature with you ability, but no you can hit multiple creatures with your hand of harm to also poison another creature. If you are able to get off an opportunity attack you could disadvantage up to 3 creatures in a turn. You also gain danger sense so now you have advantage plus evasion on most dex saves. If you want you could equip a shield. This shuts off most of your monk features, but you could still bounce action dodge if you needed to for some real tankiness. Being a dwarf with dwarvish resilience and you can turn those bonus action dodges into bonus action heals. I don’t normally consider magic items but a strength enhancing item like gauntlets of ogre strength would really help enhance the builds defense as it lets you use a shield more without hampering your debuffing as flurry of blows isn’t effected by wearing armor, but being able to use your dexterity for your to hit rolls. Plus having a high strength would also let you use reckless attack which could help you land your blows.
