Ahh.... The joys of trying to herd low-intelligence PCs through a town...

Step 1. "we want to go see the burgomeister."
Step 2. "You find his mansion surrounded by guards. They deny anyone entry."
Step 3. "Persuasion. (it fails).
Step 4. "Ask for 'guard of captains' get confused results, no clear answer even when question is clarified.
Step 5. Get told "Leave or be locked up." players leave.
Step 6. Head to a gate. Ask the guards there for the 'guard of captains' or somesuch.
Step 7. Proceed to discuss how to get past the guards around the burgomeister's mansion, while standing in front of the gate guards. Ideas that pop up include waylaying guards to take their clothes.
Step 8. Come up with the bright idea of using 'Suggestion' to convince guard to let them past and into the burgomeister's mansion.
Step 9. Discover that a spell that targets one target is not very effective when it goes against the orders the target has received, and there are 10+ other guards also there, who are not affected by the spell, with the same orders.
Step 10. Use minor illusion to try to distract the guards and create an opening to sneak in through. Two of the guards proceed to roll nat20 on perception to notice the (not particularly) sneaky monk.

To sum it up: they couldn't possibly get past the guards.