The problem
Recently I updated ubuntu 20.04 on my lenovo laptop and since the update, the wifi is disconnected at random intervals all the time. I had this problem before and disabling ipv6 according to https://askubuntu.com/a/1180403/1191580 seemed to solve it. After updating however, this solution does not work anymore. Furthermore, the wifi power saving option is already off.
Wireless adapter info:
01:00.0 Network controller: Realtek Semiconductor Co., Ltd. RTL8821CE 802.11ac PCIe Wireless Network Adapter
Subsystem: Lenovo RTL8821CE 802.11ac PCIe Wireless Network Adapter
Flags: bus master, fast devsel, latency 0, IRQ 127
I/O ports at 3000 [size=256]
Memory at a1100000 (64-bit, non-prefetchable) [size=64K]
Capabilities: <access denied>
Kernel driver in use: rtl8821ce
Kernel modules: rtl8821ce
Update:
After further investigation, I also discovered the fact that my wifi disconnected randomly when using voice/video chat software (Discord and Zoom). After several tests to verify this, I applied the suggestion as mentioned by i9pp0, which seems to have solved the problem. I hope this can help anyone else experiencing a similar problem.