If your xDSL internet connection cannot reliably withstand sustained traffic (regardless of up/download speeds, asymmetric or otherwise), you have a fault with either your router or broadband service. A “dropping” internet connection can have many external causes - all of which require proper investigation by your ISP/Line Operator.
As for backups - if automatic iCloud backups are enabled, your iPad will only perform an automatic backup while it is connected to WiFi - and to an external power source, such as your iPad Power Adapter.
The next automatic backup will occur after approximately 24 hours have elapsed since the previous backup; if not connected at this time to WiFi and power Adapter, the backup will next occur when both WiFi and power are connected. As such, while the backup period is broadly a 24 hour cycle, the iPad does not backup to a defined schedule.
For example, if your iPad performs an automatic backup at midnight, it will attempt to perform its next incremental backup 24 hours later at midnight the next day. If the iPad has no WiFi connection, or is not connected to its Power Adapter, the automatic backup will be delayed.
If the iPad is next connected to WiFi and power at 9.00am, the postponed backup will run. The next attempt to perform an automatic backup will occur at 9.00am on the subsequent day - and will occur if connected to WiFi and power at this time. If not, again the backup will be postponed until the conditions for the automatic backup are met.
As such, you can see that the backup time can be progressively skewed from a set time - but if you habitually charge your iPad overnight, if WiFi is available, a basic 24 hour backup cycle can be established.