IBS-TH5 and Tethering

I have a IBS-TH5 thermometer which has become unreliable on a tethered hotspot. I have gone through the support videos and I am able to add it to the network fine, but it stops working after a day or so. If it’s on my home network, there’s no problem and it will stay connected perpetually.

It also worked consistently well on the same network for months, but now is unreliable.

Any ideas?

Do you mean you used two phones and connected the IBS-TH5 to the hotspot of one of the phones?
If you place the IBS-TH5 next to the hotspot, can it maintain the connection?
Is the hotspot connected to other devices as well? If so, after disconnecting 2-3 WiFi devices, does the situation improve?
Please make sure the hotspot network is working.