Hi @Hugo55 Welcome to the Samsung uk Community 
Is the problem on wifi, if you have a Data Tablet you could try on Mobile Data (but only if have large Data Allowance)|
otherwise you try a Soft Reset, hold the power and Volume Down Buttons for around 10 seconds until the Device Reboots with the Samsung logo.
However you may need to reset the Network connections, General Management-Reset-Reset wifi and Bluetooth Settings or Mobile Settings.
If still no success advisable to wipe the cache partition, some temporary cache files become outmoded/corrupt . These temporary files are deleted but your Data is intact.
1. Turn off the device.
2. Connect To Computer , other Device or TV via USB-C. Press and hold the Volume Up key and then press and hold the Power key
3. When the Android logo displays, release both keys.
4. Wait until the Android system recovery menu options appear.
5. Press the Volume down key several times to highlight wipe cache partition.
6. Press Power key to select.
7. Press the Volume down key to highlight yes, them and press the Power key to select.
8. When the wipe cache partition is complete, Reboot system now is highlighted.
9. Press the Power key to restart the device.
Another idea is to try in Safe Mode https://www.samsung.com/uk/support/mobile-devices/how-to-start-my-galaxy-device-in-safe-mode/
However sometimes there are server errors which just take a bit of time to be resolved, you could also try via Smart Switch.
