I am currently using a D-Link DIR-655 Wifi router that I have to cold boot every 12-24 hrs because it reduces the data speed, creates lag or totally has no connection to the Net unless it is rebooted.

There has been a long running discussion about 2.5/5 GE on this forum (since 2016). It looks like 2.5GE+ PCI adapters are now easy to get, and there are now some USB ones, too. I ordered a €/$ 31 ...