Where to travel from Mexico ?

I am travelling to Mexico from the UK for a wedding, but I’m planning to fly out a week earlier to do some solo travelling and explore another nearby country beforehand. We’ll already be spending two weeks travelling around Mexico after the wedding, so I’d prefer somewhere outside of Mexico itself.

I’ve already been to Cuba and Costa Rica, and I’d also rather avoid the US as I’ve visited multiple times already and want to try somewhere new.

Are there any nearby countries with good flight connections to Mexico City, Tulum, or Cancún that would be the obvious choice to visit for a week, ideally somewhere with some good internet incase I need do a bit of work out there.