Okay, so your Apple Watch is being a bit stubborn about connecting to Wi-Fi. That's a pretty common little headache, actually. Here's a rundown of what's usually going on, and how to try and fix it:-
Apple Watches, generally speaking, play nicest with 2.4GHz Wi-Fi networks. So, if your router is running on a 5GHz band, that could be the issue. Sometimes routers have both, so checking your routers wifi settings is a good first step.
Your Apple Watch often relies on your iPhone to "learn" Wi-Fi networks. Basically, if your iPhone has connected to a Wi-Fi network, your watch should, in theory, be able to do the same. So, making sure your iPhone is connected to the desired wifi network is very important.
Sometimes, it's just a little digital hiccup. On your iPhone, you can "forget" the Wi-Fi network and then reconnect to it. This often helps the watch pick up the signal again.
Like with most tech, a good old restart can work wonders. Turn both your Apple Watch and your iPhone off, then back on. It's surprisingly effective.
Apple regularly releases updates that fix bugs and improve performance. So, make sure both your iPhone and Apple Watch are running the latest software.
Sometimes the problem is the router itself. Unplugging it for a minute and plugging it back in can solve many wifi issues.
If you are facing the issue after trying these solution, you should have try to follow for best instruction below.
https://thegeekpage.com/apple-watch-is-not-connecting-to-wi-fi-fix/