I’d start by rebooting everything - router, NAS, PC, Phone, any WAP’ and Ethernet switches, and all of your devices.
If you run a DDNS service then ensure that it’s updated and check that your port forwarding rules are correct.
Take a look at the server logs to look for clues about any server issues etc.
After that it’s really down to you to figure-out your own networking issues to get to the bottom of the problem - one of the drawbacks of being your server and network admin person.
As far as migrating to Blynk IoT (and by the way I’m nothing to do with Blynk), then it would probably be best to set-up a free account and do a bit of tinkering to get familiar with the differences. Take a read of this for some links to tutorials, and for a summary of the main differences between Legacy and IoT…
If you want to get more specific then I’d recommend starting a new topic of your own.
Pete.