If you are not able to connect your Trackman 4 to your iOS device, then try the following:
iOS software update
Go to Settings → General → then tap Software Update. If a Software Update is available, download and install it
Wi-Fi assist are turned off
Go to Settings → Cellular or Settings → Mobile Data. Then scroll down and tap the slider for Wi-Fi Assist
Turn off VPN
Go to Settings → General → Tap VPN. Toggle off the VPN status to “Not Connected”
TM apps enabled
Go to Settings → Privacy/Anonymity → Local Network(s) Trackman apps should be enabled