Connection timeout issue

I have 4 color LED bulbs, which had been working fine, however after I swapped to a new router (netgear d7000I have an issue and the two bulbs in the same room as the router cannot be found by the app and I cannot rediscover them - it initially suceeds, but then gets to 99% and timesout.

I had a suspicion that maybe it was due to the router being on Euro wifi band, so changed this down, but that hasnt helped. I have however found that the bulbs do work and can be connected if move to another part of the house. So I am now wondering if in the room they do not work in if there is an issue with the routers 5g wifi affecting the bulbs, which is attenuated in other rooms by the brick walls. (note I am not trying to connect to 5g). In the rest of the house I have other wifi access points supplying just 2.4 wifi.

I have tried both the Singapore and US servers with same results. If not this is there any other known factors I can explore.

Do you use the wifi network?