Odd problem with one mobile app

[#1]

After upgrading from Plusnet ADSL to fibre most things are working very well.  But on my phone (Samsunung A3 2016 also with Plusnet) there is just one app (OWL Intuition dashboard) which used to work but now connects to their server for about 200ms, grabs some historic data then drops the connection saying "Cannot connect to server"..Their app support have no idea what's going on and say no-one else is reporting a similar problem. 

So I thought I'd give you a try though it's always possible that it's a coincidence that the problem started when I changed router and moved to Fibre. Can anyone think what might be different enough to cause such odd behaviour?

Thanks - Steve

[#2]

@slewinf9 

Try separating the 2.4 and 5GHz bands, see https://community.plus.net/t5/My-Router/2-4ghz-and-or-5ghz-best-practice/m-p/1351966#M840

Try each band and use the best.

[#3]

Thanks for the idea but unfortunately the phone only supports 2.4GHz. However looking on the bright side forcing one of my laptops over to 5GHz seems to have fixed an occasional browser twitching problem.

Cheers - Steve