This issue has been discussed quite a few times in the past. If you go to the community – created wiki to the quick browse lists article, look down towards the bottom of that page for the “project report“ section and then choose the list for “router“ you can see The approaches that other people have taken. 
There are two popular methods, depending on exactly what you want to do.
1) ST Hub needs to be rebooted, but the Wi-Fi and Internet are on
The first is just to use any plug-in pocket socket which doesn’t require the smartthings hub. These are usually Wi-Fi devices that can be operated with IFTTT or with their own app. Many allow for their own schedules.
The Wemo used to be very popular, but now it looks like the integration between it and smartthings is broken, so somewhat less popular now.
Anyway, With a device like this you can cycle anything except the devices that connect you to the Internet, basically router and modem. And many of these are pretty inexpensive, like the Wemo mini which often goes on sale.
Some people have even done it with one of the Z wave relays which has an auto timer like Qubino.
2) The modem/router need to be rebooted
The second approach is normally only done for the modem/router itself, and does require a more expensive device. This is a pocket socket which regularly pings a website on the Internet, and if it can’t connect, it can be set to reboot itself. There are several brands of these.
The brand I like best, 3G store/5G store, is a little more expensive than some of the others, but allows you to choose your own website to ping rather than going to the manufacturer’s website, which is just an additional level of privacy that I like. Also, that particular brand offers their device in both US and European formats.
See the following post. It’s from 2016, but the information is still good.
There are also much more complex systems which involve fallovers and UPS and stuff like that. Those are usually less about rebooting and more about providing continuous operation in a power failure. But you’ll see them on the router list as well.