After any update it's always advisable to wipe the cache partition
https://www.samsung.com/uk/support/mobile-devices/how-do-i-clear-the-cache-on-my-device/ You could also try resetting your network settings. Search for network reset on your phone. Mines under settings>general management>reset
Depending who your network provider is, you could also check with them to see if there's any netwotk problems at this time. Might be just a coincidence.
