Your local area will have different laws than we do in Orange County, California. The best I can do, is tell you what I would do.As a landlord, I do not printernet service and I do not know what the broadband speed is and if I did, I would not know if it were sufficient for all prospective tenants. If someone asked about it or said they needed a higher broadband than average, I would give them the local internet and cable utility options and encourage them to do their own research before signing the lease.If the tenant moved in and was disappointed with the broadband service and there were no other good options, I would help them by getting a new tenant to replace them. They would be responsible to pay the rent until I was able to do so.On the other hand, If I told the tenant the broadband was fast and it was clearly inadequate, I would let them move out on a date that worked for them. I would give back the prorated rent and give them all of the deposit, after they had moved out and only make deductions from the deposit if something was damaged.