Hello and welcome to the forum!
Weird timing -
I'm assuming that your iPad is connecting fine when your router is functioning? Just trying to make sure the issue is NOT w/ your iPad - have you connected to other Wi-Fi sites on your iPad w/o a problem?
So, if your iPad can be eliminated as an issue, then the problem appears to be w/ your router and/or your ISP (Internet Service Provider) - before trying to 'guess' the problem, you might want to provide some more information, e.g. what router (brand/model) are you using, is this your home router or do you share it w/ others, where are you located and who is your ISP?
Please respond and hopefully suggestions can be given; also, I would check w/ your ISP about the timing of your outings, i.e. could this be a 'bad' router, too many on the web at those times, or other issues? Not sure - but post back & good luck!