I use a TP-Link TL-WR702N mini router to provide a wireless connection to my Nikon D4 DSLR to operate the camera remotely via my phone or tablet. The camera acts as a server when doing so.
This worked for: Archos Titanium running Android 4.3; Asus Zenpad running Android 5.0; Samsung Galaxy S3 running Android 4.3
It does not work for: Samsung Galaxy S3 running Android 7.0; Motorola Moto E running Android 6.0; Huawei P8 Lite 2017 running Android 7.0
So I believe this is an Android problem, rather than a problem with the router or device model. What happens is that I can connect to the router, but the connection drops out after a few seconds, then searches for an IP address and reconnects, and so on. Where a dialogue pops-up asking to keep the connection alive even though there is no internet, I have clicked 'yes' only for the problem to persist. I have also enabled the wifi connection to stay on when the device goes to sleep. The devices have no problem staying connected to our home router.
Does anyone know a solution?